cmd/gen-manifests: add RHSM fact to options

Add RHSM fact to image options when generating test manifests.
We add the value "test-manifest" to the API type to indicate it's a test
manifest.  This should never be registered and therefore shouldn't show
up in our data, but it's useful to detect changes and regressions in the
fact creation in the pipelines.

cmd/gen-manifests/main.go

@@ -121,6 +121,12 @@ func makeManifestJob(name string, imgType distro.ImageType, cr composeRequest, d
 			FetchChecksum: cr.OSTree.Parent,
 		}
 	}
+
+	// add RHSM fact to detect changes
+	options.Facts = &distro.FactsImageOptions{
+		ApiType: "test-manifest",
+	}
+
 	job := func(msgq chan string) (err error) {
 		defer func() {
 			msg := fmt.Sprintf("Finished job %s", filename)