Backup: Option to automatically verify backup file upon creation

[andrewdavidwong]

In most cases, it makes sense to attempt to verify your backup immediately after creating it, since a backup which can't successfully restore data is worthless. The user can already do this manually, but it would be nice to have an automatic option.

[andrewdavidwong]

I still think this option would be highly valuable for many users, specifically as a positive behavioral "nudge" to prompt them to verify their backups. Right now, most users probably aren't bothering with verification, leading to outcomes like this:

https://forum.qubes-os.org/t/corrupted-backup/7730

[andrewdavidwong]

Another case where this might have helped:

https://forum.qubes-os.org/t/qubes-backup-important-question/24343/