This adds a new authentication mode, Direct Workload Identity
Federation. This new mode permits authenticating to Google Cloud
directly using the GitHub Actions OIDC token instead of proxying through
a Google Cloud Service Account.
This changes the default behavior to enable retries. Retry logic has
existed for awhile, but required direct user action to enable. This
enables 3 retries with a fibonacci backoff of 250ms by default to handle
transient communication errors with upstream APIs.
This allows users to opt-out of exporting environment variables. This might be helpful if they **don't** want future steps to be authenticated, or if the exported environment variables conflict with other values.
* Support id token generation
* Fix id_token_audience validation
* Add id_token_audience to test workflow
* Generate dist/index.js for id token support