Select backup drive by ID

[DukemFIVE]

Is your feature request related to a problem? Please describe.
I'm always frustrated when using rsynclocal because it identifies backup drives using drive letters like sda, sdb, etc. If the drives are connected in a different order, the assigned letters can change, causing confusion and potential errors in the backup process.

Describe the solution you'd like
I would like rsynclocal to have an option to identify and assign backup drives using the unique ID of the hard drive (UUID or similar), rather than using drive letters. This would ensure that the correct drive is always targeted for backup, regardless of how the drives are connected or the order in which they are mounted.

Describe alternatives you've considered
An alternative approach could be using labels assigned to drives, but this still requires manual labeling and management. Using the unique drive ID would be a more robust and reliable solution.

Additional context
Adding this feature would improve the reliability of backup operations, especially in environments where multiple drives are frequently swapped or reconnected. This could prevent data loss and simplify the configuration process for users.