[devops] Add a download link to the Html Report entry in the GH summary comment. (#13302)

Sometimes you just need the whole thing.

tools/devops/automation/scripts/GitHub.psm1

@@ -439,7 +439,7 @@ function New-GitHubSummaryComment {
     $sb.AppendLine("* [Azure DevOps]($vstsTargetUrl)")
     if ($Env:VSDROPS_INDEX) {
         # we did generate an index with the files in vsdrops
-        $sb.AppendLine("* [Html Report (VSDrops)]($Env:VSDROPS_INDEX)")
+        $sb.AppendLine("* [Html Report (VSDrops)]($Env:VSDROPS_INDEX) [Download]($Env:SYSTEM_TEAMFOUNDATIONCOLLECTIONURI$Env:SYSTEM_TEAMPROJECT/_apis/build/builds/$Env:BUILD_BUILDID/artifacts?artifactName=HtmlReport-sim&api-version=6.0&`$format=zip)")
     }
     if (-not [string]::IsNullOrEmpty($APIDiff)) {
         WriteDiffs $sb $APIDiff