Add scripts for Windows LUCI recipe (#4303)

See flutter/flutter#89373 for context. This
sets up the script and config file to replicate the current plugins.py
recipe's behavior using the planned generic recipe.

These are currently unused, but are being landed first so that the
generic recipe has something to test against.

Part of flutter/flutter#89373

Author: stuartmorgan

.ci.yaml

@@ -39,6 +39,7 @@ targets:
     recipe: plugins/plugins
     timeout: 30
     properties:
+      target_file: windows_build_and_platform_tests.yaml
       dependencies: >
         [
           {"dependency": "vs_build"}
@@ -49,6 +50,7 @@ targets:
     recipe: plugins/plugins
     timeout: 30
     properties:
+      target_file: windows_build_and_platform_tests.yaml
       channel: stable
       dependencies: >
         [

.ci/scripts/build_examples_win32.sh

@@ -0,0 +1,7 @@
+#!/bin/bash
+# Copyright 2013 The Flutter Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+dart ./script/tool/bin/flutter_plugin_tools.dart build-examples --windows \
+   --packages-for-branch

.ci/scripts/drive_examples_win32.sh

@@ -0,0 +1,7 @@
+#!/bin/bash
+# Copyright 2013 The Flutter Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+dart ./script/tool/bin/flutter_plugin_tools.dart drive-examples --windows \
+   --packages-for-branch

.ci/scripts/prepare_tool.sh

@@ -0,0 +1,10 @@
+#!/bin/bash
+# Copyright 2013 The Flutter Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# To set FETCH_HEAD for "git merge-base" to work
+git fetch origin master
+
+cd script/tool
+dart pub get

.ci/targets/windows_build_and_platform_tests.yaml

@@ -0,0 +1,8 @@
+
+tasks:
+  - name: "prepare tool"
+    script: .ci/scripts/prepare_tool.sh
+  - name: "build examples"
+    script: .ci/scripts/build_examples_win32.sh
+  - name: "drive examples"
+    script: .ci/scripts/drive_examples_win32.sh