[TypeSpec Requirement] Fail if PR contains handwritten swagger but "stable" contains typespec-generated

[mikeharder]

• If a swagger is not typespec-generated in a PR
  • For each Swagger in stable in main:
    • If it is typespec-generated
      • PR must be typespec-generated
      • return/break
  • If GA Swaggers exist and no Swagger from TypeSpec were found
    • the swagger in the PR can be hand-written

To implement check, use the database at https://raw.githubusercontent.com/Azure/azure-sdk/main/_data/releases/latest/specs.csv, instead of querying the main git branch directly.

Example pwsh downloading DB:

https://github.com/Azure/azure-sdk-tools/blob/main/eng/common/scripts/Package-Properties.ps1#L139

[catalinaperalta]

+1. This will make the check a lot more helpful in catching corner cases where teams reverted back to swagger for any reason.