Add an example of a Cloud Run service continuously deploy from a Git repository

[minherz]

Description

Show how to create a Cloud Run service that continuously deploys from a Git repository. Demonstrate the same functionality as in the Cloud Run console page.

Context

The Cloud console provides UI to create a Cloud Run service and provision it using CD from a Git repository. This operation is not support as a single command by gcloud CLI or by Google for Terraform provider. Such example is helpful for users who are looking to leverage CD provisioning for Cloud Run service that is also reflected in the Cloud Run page in the Cloud console.

[minherz]

Synchronize with b/394013145