Add backup name to snapshot repo

[eemcmullan]

The restic repository snapshots are saved in is currently formatted as <protected-ns>/<cloned-pvc-name> which means all snapshots are in the same location for each backup. To help separate and organize, we can add the backup name, such as <protected-ns>/<backup-name>/cloned-pvc-name> https://github.com/migtools/volume-snapshot-mover/blob/master/controllers/restic.go#L87

[weshayutin]

@eemcmullan please add a few lines to the description unless you already have a related PR :) please

[mateusoliveira43]

updating line for change https://github.com/migtools/volume-snapshot-mover/blob/master/controllers/restic.go#L118