this should make sure code reuse between the OBC label controller and
the CephBucketNotification controller.
done as part of the cleanup work from:
https://github.com/rook/rook/pull/8426
this also include adding unit tests for:
- topic controller
- notification controller
- obc label controller
Signed-off-by: Yuval Lifshitz <ylifshit@redhat.com>