Refactor finalizers

[paynejacob]

Each flowtest should have a finalizer on it that is removed once all resources generated by the operator have been terminated. The operator it's self should have a finalizer on it's own deployment that is removed once the operator has deleted all flowtests. The operator deployment finalizer should be added by the operator after a successful startup. This means that if you delete the operator's deployment it will trigger the operator deleting all flowtests. This will in turn trigger all resources generated by the operator being deleted.