sagemathgh-36954: `tox -e update_docker_platforms`
    
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Please provide a concise, informative and self-explanatory title.
Don't put issue numbers in there, do this in the PR body below.
For example, instead of "Fixes sagemath#1234" use "Introduce new method to
calculate 1+1"
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<!-- Describe your changes here in detail -->

Furthering my hidden agenda of bringing portability tools to the masses.

- We add `.devcontainer/portability-*/devcontainer.json` files for all
platforms tested in our CI. This makes them selectable in GitHub
Codespaces.
- The files are generated by the new command `tox -e
update_docker_platforms`, which also updates the workflow file
`.github/workflows/docker.yml`.
- The command also [adds a table to the portability testing section in
the developer's guide](https://deploy-preview-36954--
sagemath.netlify.app/html/en/developer/portability_testing#using-our-
pre-built-docker-images-published-on-ghcr-io) with links to GitHub
Packages and friendly "Run in GitHub Codespaces" buttons.
- Because 'tis the season of Spielzeugneid, [we document how to run the
portability testing in GitHub Codespaces via Docker-in-
Docker](https://deploy-preview-36954--
sagemath.netlify.app/html/en/developer/portability_testing#testing-sage-
on-a-different-platform-using-docker), useful for those who cannot run
Docker on their own computers. This uses a new devcontainer config "tox-
docker-in-docker".
- We make various other updates to the portability testing section in
the developer's guide.

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example "Fixes sagemath#12345". -->
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appropriately. -->

### 📝 Checklist

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appropriately -->
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here to help! -->
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- [x] The title is concise, informative, and self-explanatory.
- [x] The description explains in detail what this PR is about.
- [ ] I have linked a relevant issue or discussion.
- [ ] I have created tests covering the changes.
- [ ] I have updated the documentation accordingly.

### ⌛ Dependencies

<!-- List all open PRs that this PR logically depends on
- sagemath#12345: short description why this is a dependency
- sagemath#34567: ...
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- Depends on sagemath#37030 (split out from here)

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URL: sagemath#36954
Reported by: Matthias Köppe
Reviewer(s): Kwankyu Lee, Matthias Köppe, Tobias Diez

.devcontainer/portability-almalinux-8-python3.9-minimal/devcontainer.json

@@ -0,0 +1,25 @@
+// The command "tox -e update_docker_platforms"
+//   creates .devcontainer/portability-*-*/devcontainer.json
+//      from .devcontainer/portability-devcontainer.json.in
+// See https://aka.ms/devcontainer.json for format details.
+{
+    "name": "almalinux-8-python3.9-minimal (≥ 8-core)",
+    "build": {
+        "dockerfile": "portability-Dockerfile",
+        // See tox.ini for definitions
+        "args": {
+            "SYSTEM_FACTOR": "almalinux-8-python3.9",
+            "PACKAGE_FACTOR": "minimal",
+            "DOCKER_TARGET": "with-targets",
+            "DOCKER_TAG": "dev"
+        }
+    },
+    "containerEnv": {
+        "MAKE": "make -j4"
+    },
+    "onCreateCommand": ".devcontainer/onCreate.sh",
+    "updateContentCommand": ".devcontainer/portability-updateContent.sh",
+    "extensions": [
+        "ms-python.python"
+    ]
+}

.devcontainer/portability-almalinux-8-python3.9-minimal/portability-Dockerfile

@@ -0,0 +1 @@
+../portability-Dockerfile

.devcontainer/portability-almalinux-8-python3.9-standard/devcontainer.json

@@ -0,0 +1,25 @@
+// The command "tox -e update_docker_platforms"
+//   creates .devcontainer/portability-*-*/devcontainer.json
+//      from .devcontainer/portability-devcontainer.json.in
+// See https://aka.ms/devcontainer.json for format details.
+{
+    "name": "almalinux-8-python3.9-standard (≥ 8-core)",
+    "build": {
+        "dockerfile": "portability-Dockerfile",
+        // See tox.ini for definitions
+        "args": {
+            "SYSTEM_FACTOR": "almalinux-8-python3.9",
+            "PACKAGE_FACTOR": "standard",
+            "DOCKER_TARGET": "with-targets",
+            "DOCKER_TAG": "dev"
+        }
+    },
+    "containerEnv": {
+        "MAKE": "make -j4"
+    },
+    "onCreateCommand": ".devcontainer/onCreate.sh",
+    "updateContentCommand": ".devcontainer/portability-updateContent.sh",
+    "extensions": [
+        "ms-python.python"
+    ]
+}

.devcontainer/portability-almalinux-8-python3.9-standard/portability-Dockerfile

@@ -0,0 +1 @@
+../portability-Dockerfile

.devcontainer/portability-almalinux-9-python3.11-minimal/devcontainer.json

@@ -0,0 +1,25 @@
+// The command "tox -e update_docker_platforms"
+//   creates .devcontainer/portability-*-*/devcontainer.json
+//      from .devcontainer/portability-devcontainer.json.in
+// See https://aka.ms/devcontainer.json for format details.
+{
+    "name": "almalinux-9-python3.11-minimal (≥ 8-core)",
+    "build": {
+        "dockerfile": "portability-Dockerfile",
+        // See tox.ini for definitions
+        "args": {
+            "SYSTEM_FACTOR": "almalinux-9-python3.11",
+            "PACKAGE_FACTOR": "minimal",
+            "DOCKER_TARGET": "with-targets",
+            "DOCKER_TAG": "dev"
+        }
+    },
+    "containerEnv": {
+        "MAKE": "make -j4"
+    },
+    "onCreateCommand": ".devcontainer/onCreate.sh",
+    "updateContentCommand": ".devcontainer/portability-updateContent.sh",
+    "extensions": [
+        "ms-python.python"
+    ]
+}

.devcontainer/portability-almalinux-9-python3.11-minimal/portability-Dockerfile

@@ -0,0 +1 @@
+../portability-Dockerfile

.devcontainer/portability-almalinux-9-python3.11-standard/devcontainer.json

@@ -0,0 +1,25 @@
+// The command "tox -e update_docker_platforms"
+//   creates .devcontainer/portability-*-*/devcontainer.json
+//      from .devcontainer/portability-devcontainer.json.in
+// See https://aka.ms/devcontainer.json for format details.
+{
+    "name": "almalinux-9-python3.11-standard (≥ 8-core)",
+    "build": {
+        "dockerfile": "portability-Dockerfile",
+        // See tox.ini for definitions
+        "args": {
+            "SYSTEM_FACTOR": "almalinux-9-python3.11",
+            "PACKAGE_FACTOR": "standard",
+            "DOCKER_TARGET": "with-targets",
+            "DOCKER_TAG": "dev"
+        }
+    },
+    "containerEnv": {
+        "MAKE": "make -j4"
+    },
+    "onCreateCommand": ".devcontainer/onCreate.sh",
+    "updateContentCommand": ".devcontainer/portability-updateContent.sh",
+    "extensions": [
+        "ms-python.python"
+    ]
+}

.devcontainer/portability-almalinux-9-python3.11-standard/portability-Dockerfile

@@ -0,0 +1 @@
+../portability-Dockerfile

.devcontainer/portability-archlinux-latest-minimal/devcontainer.json

@@ -0,0 +1,25 @@
+// The command "tox -e update_docker_platforms"
+//   creates .devcontainer/portability-*-*/devcontainer.json
+//      from .devcontainer/portability-devcontainer.json.in
+// See https://aka.ms/devcontainer.json for format details.
+{
+    "name": "archlinux-latest-minimal (≥ 8-core)",
+    "build": {
+        "dockerfile": "portability-Dockerfile",
+        // See tox.ini for definitions
+        "args": {
+            "SYSTEM_FACTOR": "archlinux-latest",
+            "PACKAGE_FACTOR": "minimal",
+            "DOCKER_TARGET": "with-targets",
+            "DOCKER_TAG": "dev"
+        }
+    },
+    "containerEnv": {
+        "MAKE": "make -j4"
+    },
+    "onCreateCommand": ".devcontainer/onCreate.sh",
+    "updateContentCommand": ".devcontainer/portability-updateContent.sh",
+    "extensions": [
+        "ms-python.python"
+    ]
+}

.devcontainer/portability-archlinux-latest-minimal/portability-Dockerfile

@@ -0,0 +1 @@
+../portability-Dockerfile

.devcontainer/portability-archlinux-latest-standard/devcontainer.json

@@ -0,0 +1,25 @@
+// The command "tox -e update_docker_platforms"
+//   creates .devcontainer/portability-*-*/devcontainer.json
+//      from .devcontainer/portability-devcontainer.json.in
+// See https://aka.ms/devcontainer.json for format details.
+{
+    "name": "archlinux-latest-standard (≥ 8-core)",
+    "build": {
+        "dockerfile": "portability-Dockerfile",
+        // See tox.ini for definitions
+        "args": {
+            "SYSTEM_FACTOR": "archlinux-latest",
+            "PACKAGE_FACTOR": "standard",
+            "DOCKER_TARGET": "with-targets",
+            "DOCKER_TAG": "dev"
+        }
+    },
+    "containerEnv": {
+        "MAKE": "make -j4"
+    },
+    "onCreateCommand": ".devcontainer/onCreate.sh",
+    "updateContentCommand": ".devcontainer/portability-updateContent.sh",
+    "extensions": [
+        "ms-python.python"
+    ]
+}

.devcontainer/portability-archlinux-latest-standard/portability-Dockerfile

@@ -0,0 +1 @@
+../portability-Dockerfile

.devcontainer/portability-centos-7-devtoolset-gcc_11-minimal/devcontainer.json

@@ -0,0 +1,25 @@
+// The command "tox -e update_docker_platforms"
+//   creates .devcontainer/portability-*-*/devcontainer.json
+//      from .devcontainer/portability-devcontainer.json.in
+// See https://aka.ms/devcontainer.json for format details.
+{
+    "name": "centos-7-devtoolset-gcc_11-minimal (≥ 8-core)",
+    "build": {
+        "dockerfile": "portability-Dockerfile",
+        // See tox.ini for definitions
+        "args": {
+            "SYSTEM_FACTOR": "centos-7-devtoolset-gcc_11",
+            "PACKAGE_FACTOR": "minimal",
+            "DOCKER_TARGET": "with-targets",
+            "DOCKER_TAG": "dev"
+        }
+    },
+    "containerEnv": {
+        "MAKE": "make -j4"
+    },
+    "onCreateCommand": ".devcontainer/onCreate.sh",
+    "updateContentCommand": ".devcontainer/portability-updateContent.sh",
+    "extensions": [
+        "ms-python.python"
+    ]
+}

.devcontainer/portability-centos-7-devtoolset-gcc_11-minimal/portability-Dockerfile

@@ -0,0 +1 @@
+../portability-Dockerfile

.devcontainer/portability-centos-7-devtoolset-gcc_11-standard/devcontainer.json

@@ -0,0 +1,25 @@
+// The command "tox -e update_docker_platforms"
+//   creates .devcontainer/portability-*-*/devcontainer.json
+//      from .devcontainer/portability-devcontainer.json.in
+// See https://aka.ms/devcontainer.json for format details.
+{
+    "name": "centos-7-devtoolset-gcc_11-standard (≥ 8-core)",
+    "build": {
+        "dockerfile": "portability-Dockerfile",
+        // See tox.ini for definitions
+        "args": {
+            "SYSTEM_FACTOR": "centos-7-devtoolset-gcc_11",
+            "PACKAGE_FACTOR": "standard",
+            "DOCKER_TARGET": "with-targets",
+            "DOCKER_TAG": "dev"
+        }
+    },
+    "containerEnv": {
+        "MAKE": "make -j4"
+    },
+    "onCreateCommand": ".devcontainer/onCreate.sh",
+    "updateContentCommand": ".devcontainer/portability-updateContent.sh",
+    "extensions": [
+        "ms-python.python"
+    ]
+}

.devcontainer/portability-centos-7-devtoolset-gcc_11-standard/portability-Dockerfile

@@ -0,0 +1 @@
+../portability-Dockerfile

.devcontainer/portability-centos-stream-8-python3.9-minimal/devcontainer.json

@@ -0,0 +1,25 @@
+// The command "tox -e update_docker_platforms"
+//   creates .devcontainer/portability-*-*/devcontainer.json
+//      from .devcontainer/portability-devcontainer.json.in
+// See https://aka.ms/devcontainer.json for format details.
+{
+    "name": "centos-stream-8-python3.9-minimal (≥ 8-core)",
+    "build": {
+        "dockerfile": "portability-Dockerfile",
+        // See tox.ini for definitions
+        "args": {
+            "SYSTEM_FACTOR": "centos-stream-8-python3.9",
+            "PACKAGE_FACTOR": "minimal",
+            "DOCKER_TARGET": "with-targets",
+            "DOCKER_TAG": "dev"
+        }
+    },
+    "containerEnv": {
+        "MAKE": "make -j4"
+    },
+    "onCreateCommand": ".devcontainer/onCreate.sh",
+    "updateContentCommand": ".devcontainer/portability-updateContent.sh",
+    "extensions": [
+        "ms-python.python"
+    ]
+}

.devcontainer/portability-centos-stream-8-python3.9-minimal/portability-Dockerfile

@@ -0,0 +1 @@
+../portability-Dockerfile

.devcontainer/portability-centos-stream-8-python3.9-standard/devcontainer.json

@@ -0,0 +1,25 @@
+// The command "tox -e update_docker_platforms"
+//   creates .devcontainer/portability-*-*/devcontainer.json
+//      from .devcontainer/portability-devcontainer.json.in
+// See https://aka.ms/devcontainer.json for format details.
+{
+    "name": "centos-stream-8-python3.9-standard (≥ 8-core)",
+    "build": {
+        "dockerfile": "portability-Dockerfile",
+        // See tox.ini for definitions
+        "args": {
+            "SYSTEM_FACTOR": "centos-stream-8-python3.9",
+            "PACKAGE_FACTOR": "standard",
+            "DOCKER_TARGET": "with-targets",
+            "DOCKER_TAG": "dev"
+        }
+    },
+    "containerEnv": {
+        "MAKE": "make -j4"
+    },
+    "onCreateCommand": ".devcontainer/onCreate.sh",
+    "updateContentCommand": ".devcontainer/portability-updateContent.sh",
+    "extensions": [
+        "ms-python.python"
+    ]
+}

.devcontainer/portability-centos-stream-8-python3.9-standard/portability-Dockerfile

@@ -0,0 +1 @@
+../portability-Dockerfile

.devcontainer/portability-centos-stream-9-python3.9-minimal/devcontainer.json

@@ -0,0 +1,25 @@
+// The command "tox -e update_docker_platforms"
+//   creates .devcontainer/portability-*-*/devcontainer.json
+//      from .devcontainer/portability-devcontainer.json.in
+// See https://aka.ms/devcontainer.json for format details.
+{
+    "name": "centos-stream-9-python3.9-minimal (≥ 8-core)",
+    "build": {
+        "dockerfile": "portability-Dockerfile",
+        // See tox.ini for definitions
+        "args": {
+            "SYSTEM_FACTOR": "centos-stream-9-python3.9",
+            "PACKAGE_FACTOR": "minimal",
+            "DOCKER_TARGET": "with-targets",
+            "DOCKER_TAG": "dev"
+        }
+    },
+    "containerEnv": {
+        "MAKE": "make -j4"
+    },
+    "onCreateCommand": ".devcontainer/onCreate.sh",
+    "updateContentCommand": ".devcontainer/portability-updateContent.sh",
+    "extensions": [
+        "ms-python.python"
+    ]
+}

.devcontainer/portability-centos-stream-9-python3.9-minimal/portability-Dockerfile

@@ -0,0 +1 @@
+../portability-Dockerfile

.devcontainer/portability-centos-stream-9-python3.9-standard/devcontainer.json

@@ -0,0 +1,25 @@
+// The command "tox -e update_docker_platforms"
+//   creates .devcontainer/portability-*-*/devcontainer.json
+//      from .devcontainer/portability-devcontainer.json.in
+// See https://aka.ms/devcontainer.json for format details.
+{
+    "name": "centos-stream-9-python3.9-standard (≥ 8-core)",
+    "build": {
+        "dockerfile": "portability-Dockerfile",
+        // See tox.ini for definitions
+        "args": {
+            "SYSTEM_FACTOR": "centos-stream-9-python3.9",
+            "PACKAGE_FACTOR": "standard",
+            "DOCKER_TARGET": "with-targets",
+            "DOCKER_TAG": "dev"
+        }
+    },
+    "containerEnv": {
+        "MAKE": "make -j4"
+    },
+    "onCreateCommand": ".devcontainer/onCreate.sh",
+    "updateContentCommand": ".devcontainer/portability-updateContent.sh",
+    "extensions": [
+        "ms-python.python"
+    ]
+}

.devcontainer/portability-centos-stream-9-python3.9-standard/portability-Dockerfile

@@ -0,0 +1 @@
+../portability-Dockerfile

.devcontainer/portability-conda-forge-python3.11-minimal/devcontainer.json

@@ -0,0 +1,25 @@
+// The command "tox -e update_docker_platforms"
+//   creates .devcontainer/portability-*-*/devcontainer.json
+//      from .devcontainer/portability-devcontainer.json.in
+// See https://aka.ms/devcontainer.json for format details.
+{
+    "name": "conda-forge-python3.11-minimal (≥ 8-core)",
+    "build": {
+        "dockerfile": "portability-Dockerfile",
+        // See tox.ini for definitions
+        "args": {
+            "SYSTEM_FACTOR": "conda-forge-python3.11",
+            "PACKAGE_FACTOR": "minimal",
+            "DOCKER_TARGET": "with-targets",
+            "DOCKER_TAG": "dev"
+        }
+    },
+    "containerEnv": {
+        "MAKE": "make -j4"
+    },
+    "onCreateCommand": ".devcontainer/onCreate.sh",
+    "updateContentCommand": ".devcontainer/portability-updateContent.sh",
+    "extensions": [
+        "ms-python.python"
+    ]
+}

.devcontainer/portability-conda-forge-python3.11-minimal/portability-Dockerfile

@@ -0,0 +1 @@
+../portability-Dockerfile