Workload Identity federation - integrated with IAM

[ChrisPates]

Is your feature request related to a problem? Please describe.
Pull Request #150 feat: use workload identity federation to gain access to google has already demonstrated the changes required, however it is currently a very breaking change.

Describe the solution you'd like
Accept the above PR into a feature branch, then:

• re-instate the existing mechanism alongside it.
• update QuickStarts Templates to use the method
• update documentation
• lab guide to show this method

Creating the WIF trust with an IAM Role

• Configure Workload Identity Federation with AWS
  The instructions here are a little ambiguous and focus on ec2 rather than Lambda.

Cleanest approach (no impersonation)

• Deploying Workload Identity Federation between AWS and GCP - Probably the cleanest method
• Access Google Cloud Storage from AWS Lambda using Workload Identity Federation

Alternate approach but still requires impersonation

• Authenticating to Google Cloud from an AWS Lambda function
• From AWS Lambda to GCS: Keyless Multi-Cloud Access with Outbound Identity Federation