Automatic deletion of remote backups after expiration

Currently, only backups on local archive volumes are deleted automatically after expiration. The automated cleanup process is triggered after every database backup run.

Backups on remote volumes are not deleted automatically. Cleanup processes have to be executed manually on the remote side or automated based on the expiration info file that is included in every database backup.

To provide a central handling of the backup deletion processes in EXASuite, we add support for cleanup processes on remote volumes.
This feature can be enabled by setting the cleanvolume option on the corresponding remote archive volume.