Add buildMetadata task and ref (#5511)

* Add buildMetadata task and ref

Move build metadata tasks, draft buildMetadata reference

Clean up buildMetadata ref

Add managed by label task

Add local non-generated task

Add local generated resource

Add remote generator task

Clean up tasks and ref

Add local transformer annotation example

Add local and remote transformer example

* Address PR feedback and general cleanup

cherrypick updates from feature branch

fix script

fix release script

cmd/gorepomod/internal/git/runner.go

@@ -258,7 +258,8 @@ func (gr *Runner) AssureOnMainBranch() error {
 // CheckoutMainBranch does that.
 func (gr *Runner) CheckoutMainBranch() error {
 	gr.comment("checking out main branch")
-	return gr.runNoOut(noHarmDone, "checkout", mainBranch)
+	fullBranchSpec := fmt.Sprintf("%s/%s", remoteOrigin, mainBranch)
+	return gr.runNoOut(noHarmDone, "checkout", fullBranchSpec)
 }
 
 // FetchRemote does that.