Add a way to clean up volumes if cinder host goes offline or is decommissioned
Today, if a cinder host with volumes goes offline or is decommissioned on purpose without cleanly removing it from platform9 (by deleting all volumes and volume-snapshots and then deauthorizing the host), then there is no way to clean it up from the UI.
Offline host with cinder volumes present cannot be deauthorized from the UI.
If one tries to delete volumes, they get stuck in deleting state forever.
We should have a way to clean up a cinder host if it is goes offline.