integrate dbrm backup into columnstore main engine

Currently we have 2 Versions of the dbrm

save, saveA and SaveB, so 1 active and 2 backups.

The old system of only 2 backups by restart is not sufficient.

• If a customer restarted multiple time, all working backups can be deleted.

• A backup will be saved after a full restart, if a system was not restarted long time, the last backup is too old.

A sceduled backup should be integrated into main columnstore main system,
available on default after fresh installation with reasonable default values.

Also the load of a backup should be easier for a DBA, best with a 1 liner.

So the backup should not labelled with A and B, it should be labelled with active and backup with timestamp.

Loading should be possible with a timestamp, so the latest for the desired timestamp can be loaded