Move the discovery client to its own package

pkg/api/unversioned/helpers.go

@@ -92,3 +92,13 @@ func FormatLabelSelector(labelSelector *LabelSelector) string {
 	}
 	return l
 }
+
+func ExtractGroupVersions(l *APIGroupList) []string {
+	var groupVersions []string
+	for _, g := range l.Groups {
+		for _, gv := range g.Versions {
+			groupVersions = append(groupVersions, gv.GroupVersion)
+		}
+	}
+	return groupVersions
+}