Add labels support

[william-msft]

This PR introduces the necessary plumbing to propagate the TargetLabel parameter from the Azure SourceControls API all the way through to the az CLI command that performs the deployment.
This is a high level flow:

[1. Portal] 
     ↓
[2. Azure SourceControls API]
     ↓
[3. Generate GitHub Action YAML]
     ↓
[4. GitHub Action Triggered with YAML]
     ↓
[5. container-apps-deploy-action runs]
     ↓
[6. az CLI executed to deploy app]

PR for steps 5 & 6:

• Add labels support #127

Additionally, this PR fixes authentication failures: