Add support for regional secrets list datasource google_secret_manager_regional_secrets

[abheda-crest]

Add support for regional secrets list datasource google_secret_manager_regional_secrets.
More info about regional secrets: https://cloud.google.com/secret-manager/docs/regional-secrets-overview

Release Note Template for Downstream PRs (will be copied)

`google_secret_manager_regional_secrets`

[github-actions]

Hello! I am a robot. Tests will require approval from a repository maintainer to run.

@ScottSuarez, a repository maintainer, has been assigned to review your changes. If you have not received review feedback within 2 business days, please leave a comment on this PR asking them to take a look.

You can help make sure that review is quick by doing a self-review and by running impacted tests locally.

[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.

google provider: Diff ( 4 files changed, 520 insertions(+))
google-beta provider: Diff ( 4 files changed, 520 insertions(+))

[modular-magician]

Tests analytics

Total tests: 41
Passed tests: 37
Skipped tests: 2
Affected tests: 2

Click here to see the affected service packages

• secretmanagerregional

Action taken

Found 2 affected test(s) by replaying old test recordings. Starting RECORDING based on the most recent commit. Click here to see the affected tests

• TestAccDataSourceSecretManagerRegionalRegionalSecrets_basic
• TestAccDataSourceSecretManagerRegionalRegionalSecrets_filter

Get to know how VCR tests work

[modular-magician]

$\textcolor{green}{\textsf{Tests passed during RECORDING mode:}}$
TestAccDataSourceSecretManagerRegionalRegionalSecrets_basic[Debug log]
TestAccDataSourceSecretManagerRegionalRegionalSecrets_filter[Debug log]

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

---

$\textcolor{green}{\textsf{All tests passed!}}$

View the build log or the debug log for each test

[ScottSuarez]

Can I ask for my information about your usecase? How are are you looking to use and interact with this datasource?

[abheda-crest]

Can I ask for my information about your usecase? How are are you looking to use and interact with this datasource?

This datasource enables the retrieval of regional secrets for a specified location. It is particularly valuable for users who want to filter regional secrets using specific parameters and leverage these values in other resources (e.g. to fetch secret version based on the name of the filtered regional secrets). Moreover, It is regional equivalent of the datasource google_secret_manager_secrets.
References: hashicorp/terraform-provider-google#14556 & #9099

[gptSanyam]

LGTM