Added support for the integration with Secret Manager in Cloud Run.

[modular-magician]

The integration enables binding secret values to environment variables or
to the content of files.

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Release Note Template for Downstream PRs (will be copied)

cloudrun: added support to bind secrets from Secret Manager to environment variables or files to `google_cloud_run_service`

Derived from GoogleCloudPlatform/magic-modules#4739

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