[Bug]: No way to exclude stages for an environments in GitHub Action Workflows

### Affected Area

GitHub Actions Workflows

### Description

Unlike Azure DevOps, there is no way to select which stages to run on GitHub Action workflows.

It is important that we have the ability to do so in order to avoid execution failures of some workflows when the depenency workflows have not been executed on this stage (i.e. policy assignment workflow will fail on the build stage for prod stages if any policy definitions and initiatives are not deployed in prod environment)

### Steps to Reproduce

1. Create a new policy definition in a feature branch
2. Add the new policy to an existing initiative in the same feature branch
3. run the policy defintion workflow from the feature branch
4. run the policy initiative workflow from the feature branch
5. run the policy assignment workflow from the feature branch

### Expected Behavior

Policy assignment workflow will fail

### Actual Behavior

Need to have the ability to exclude policy assignment prod build stage

### Bicep CLI Version

_No response_

### PowerShell Version

_No response_

### CI/CD Platform

GitHub Actions

### Additional Context

_No response_