Support named databases for Firestore

[bw-yuhogg]

This adds named database support for Firestore databases.
No actual Terraform code needs to be changed for this to occur, this is purely a matter of documentation and testing.

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). Just documentation/testing, so not needed
• 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). N/A
• Generated Terraform providers, and ran make test and make lint in the generated providers to ensure it passes unit and linter tests.
• Ran relevant acceptance tests using my own Google Cloud project and credentials (If the acceptance tests do not yet pass or you are unable to run them, please let your reviewer know). Tests not yet passing locally
• Read Write release notes before writing my release note below.

Release Note Template for Downstream PRs (will be copied)

[modular-magician]

Hello! I am a robot who works on Magic Modules PRs.

I've detected that you're a community contributor. @slevenick, a repository maintainer, has been assigned to assist you and help review your changes.

❓ First time contributing? Click here for more details

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Your assigned reviewer will help review your code by:

• Ensuring it's backwards compatible, covers common error cases, etc.
• Summarizing the change into a user-facing changelog note.
• Passes tests, either our "VCR" suite, a set of presubmit tests, or with manual test runs.

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[modular-magician]

Hi there, I'm the Modular magician. I've detected the following information about your changes:

Diff report

Your PR generated some diffs in downstreams - here they are.

Terraform GA: Diff ( 2 files changed, 224 insertions(+), 31 deletions(-))
Terraform Beta: Diff ( 2 files changed, 224 insertions(+), 31 deletions(-))
TF Conversion: Diff ( 2 files changed, 3 insertions(+), 3 deletions(-))

[modular-magician]

Hi there, I'm the Modular magician. I've detected the following information about your changes:

Diff report

Your PR generated some diffs in downstreams - here they are.

Terraform GA: Diff ( 2 files changed, 219 insertions(+), 28 deletions(-))
Terraform Beta: Diff ( 2 files changed, 219 insertions(+), 28 deletions(-))
TF Conversion: Diff ( 2 files changed, 3 insertions(+), 3 deletions(-))

[slevenick]

I'm not reviewing as this is marked as draft. Please re-request review when this is ready for me to take a look

[modular-magician]

Tests analytics

Total tests: 2855
Passed tests 2552
Skipped tests: 297
Affected tests: 6

Action taken

Found 6 affected test(s) by replaying old test recordings. Starting RECORDING based on the most recent commit. Click here to see the affected tests

TestAccFirestoreDatabase_firestoreDatabaseInDatastoreModeExample|TestAccFirestoreDatabase_firestoreDefaultDatabaseExample|TestAccFirestoreDatabase_firestoreDatabaseExample|TestAccFirestoreDatabase_firestoreDefaultDatabaseInDatastoreModeExample|TestAccComputeFirewallPolicyRule_multipleRules|TestAccContainerAwsNodePool_BetaBasicHandWritten

Get to know how VCR tests work

[modular-magician]

$\textcolor{green}{\textsf{Tests passed during RECORDING mode:}}$
TestAccFirestoreDatabase_firestoreDatabaseInDatastoreModeExample[Debug log]
TestAccFirestoreDatabase_firestoreDefaultDatabaseExample[Debug log]
TestAccFirestoreDatabase_firestoreDatabaseExample[Debug log]
TestAccFirestoreDatabase_firestoreDefaultDatabaseInDatastoreModeExample[Debug log]

Rerun these tests in REPLAYING mode to catch issues

$\textcolor{green}{\textsf{No issues found for passed tests after REPLAYING rerun.}}$

---

$\textcolor{red}{\textsf{Tests failed during RECORDING mode:}}$
TestAccComputeFirewallPolicyRule_multipleRules[Error message] [Debug log]
TestAccContainerAwsNodePool_BetaBasicHandWritten[Error message] [Debug log]

$\textcolor{red}{\textsf{Please fix these to complete your PR.}}$
View the build log or the debug log for each test

[slevenick]

Removed the release note as there are no user-facing changes except for docs.

Thanks!