release-engineering: package (during build) and upload GPO templates (#18841)

I've been doing this manually. It is time for me to do it not-manually.

build/pipelines/templates-v2/job-merge-msix-into-bundle.yml

@@ -147,6 +147,10 @@ jobs:
         ValidateSignature: true
         Verbosity: 'Verbose'
 
+  - pwsh: |-
+      tar -c -v --format=zip -f "$(JobOutputDirectory)/GroupPolicyTemplates_$(XES_APPXMANIFESTVERSION).zip" -C "$(Build.SourcesDirectory)/policies" *
+    displayName: Package GPO Templates
+
   - ${{ parameters.afterBuildSteps }}
 
   - ${{ if eq(parameters.publishArtifacts, true) }}: