Make tpgtools spit out working documentation.

[nat-henderson]

In order for KCC to depend on a tpgtools resource, tpgtools needs to fix the longstanding-but-low-priority bug with documentation escaping. It turns out not to be too hard since go doesn't have a whole lot of necessary escape sequences - just ", \, and newlines. Made it a function that's easy to work with if we find more that we need to add, although I was going based on https://golang.org/ref/spec#String_literals so it should be pretty correct.

Fixes hashicorp/terraform-provider-google#9197.

If this PR is for Terraform, I acknowledge that I have:

• Searched through the issue tracker for an open issue that this either resolves or contributes to, commented on it to claim it, and written "fixes {url}" or "part of {url}" in this PR description. If there were no relevant open issues, I opened one and commented that I would like to work on it (not necessary for very small changes).
• Generated Terraform, and ran make test and make lint to ensure it passes unit and linter tests.
• Ensured that all new fields I added that can be set by a user appear in at least one example (for generated resources) or third_party test (for handwritten resources or update tests).
• Ran relevant acceptance tests (If the acceptance tests do not yet pass or you are unable to run them, please let your reviewer know).
• Read the Release Notes Guide before writing my release note below.

Release Note Template for Downstream PRs (will be copied)

[modular-magician]

Hi! I'm the modular magician. Your PR generated some diffs in downstreams - here they are.

Diff report:

Terraform GA: Diff ( 7 files changed, 301 insertions(+), 301 deletions(-))
Terraform Beta: Diff ( 10 files changed, 358 insertions(+), 358 deletions(-))

[modular-magician]

Hi! I'm the modular magician. Your PR generated some diffs in downstreams - here they are.

Diff report:

Terraform GA: Diff ( 7 files changed, 301 insertions(+), 301 deletions(-))
Terraform Beta: Diff ( 11 files changed, 360 insertions(+), 359 deletions(-))

[nat-henderson]

Another oom issue in TeamCity. This diff is all just description stuff, am I okay to merge without running those tests or do I need to wait for them?

[nat-henderson]

Ah, might as well just go again. /gcbrun

[modular-magician]

Hi! I'm the modular magician. Your PR generated some diffs in downstreams - here they are.

Diff report:

Terraform GA: Diff ( 7 files changed, 301 insertions(+), 301 deletions(-))
Terraform Beta: Diff ( 11 files changed, 359 insertions(+), 359 deletions(-))

[slevenick]

Another oom issue in TeamCity. This diff is all just description stuff, am I okay to merge without running those tests or do I need to wait for them?

I'd just go for it, the only danger here would be non-compiling resources but that would show up real quickly!

[nat-henderson]

Will do, thanks. The test as it stands seems to prove that it does compile at least!

[modular-magician]

I have triggered VCR tests in RECORDING mode for the following tests that failed during VCR: TestAccComputeOrganizationSecurityPolicyAssociation_organizationSecurityPolicyAssociationBasicExample|TestAccFirebaseWebApp_firebaseWebAppBasicExample|TestAccTags You can view the result here: https://ci-oss.hashicorp.engineering/viewQueued.html?itemId=204729

[modular-magician]

Tests failed during RECORDING mode: TestAccFirebaseWebApp_firebaseWebAppBasicExample|TestAccComputeOrganizationSecurityPolicyAssociation_organizationSecurityPolicyAssociationBasicExample Please fix these to complete your PR