Implement segment hot backup & restore w/ DBRM backups

Implement segment hot backup to be optionally included with DBRM backups

The goal of this is to enable more consistent hot backups by having the most recent segments of all table/columns so that when we restore the metadata,
vbbm/vss/journal are more consistent with the active states of files on disk from the time of the backup. Helping the most recently changed files be more accurate after restoring.