add a codeowners file to dart-lang/labs (#186)

Co-authored-by: Jonas Finnemann Jensen <[email protected]>

Author: devoncarew

CODEOWNERS

@@ -0,0 +1,8 @@
+# Below are suggested reviewers for PRs to packages in this repository.
+#
+# These are suggestions; it is fine to have your changes reviewed by someone
+# else.
+
+/pkgs/appengine/               @dart-lang/dart-pub-team
+/pkgs/gcloud/                  @dart-lang/dart-pub-team
+/pkgs/native_synchronization/  @mraleph