Add scripts to update Azure US Government policy library

[sshockley]

Overview/Summary

Add scripts to import policy library for Azure US Government

Related Issues/Work Items

Partially fixes #825
Also includes fix #324 which should probably also be applied to Invoke-PolicyToBicep-China.ps1

This PR fixes/adds/changes/removes

Adds github workflow to create scheduled PRs (based on update-policy-china.yml)
Adds two scripts needed by workflow (based on China versions)

Breaking Changes

N/A

Testing Evidence

Tested using local scripts, Github workflow is untested. Still needs deployment testing.

As part of this Pull Request I have

• Read the Contribution Guide and ensured this PR is compliant with the guide
• Ensured the resource API versions in .bicep file/s I am adding/editing are using the latest API version possible
• Checked for duplicate Pull Requests
• Associated it with relevant GitHub Issues
• (ALZ Bicep Core Team Only) Associated it with relevant ADO Items
• Ensured my code/branch is up-to-date with the latest changes in the main branch
• Performed testing and provided evidence.
• Updated one or more of the following tests (if required)
  • Unit
  • Linting
  • E2E (End-To-End)
  • ValidateAzCloud (Base validation in Azure Cloud)
  • ValidateMcCloud (Base validation in Azure China Cloud)
• Updated relevant and associated documentation (e.g. Contribution Guide, Module READMEs, Wiki Docs etc.)
• If relevant, created or updated Code Tours here

[sshockley]

This PR doesn't include the files created by the workflow, since that would make it more difficult to review. I did have to manually create the subfolders as the script doesn't handle that.

[oZakari]

Hey @sshockley, we are working on adding support for Azure US Gov. Will build upon your great work so far in this PR. 👍🏼