Allow doing a backup of the Persistent Storage when cloning
We already have a design on the blueprint (https://tails.boum.org/blueprint/backups) so there's not much UX work left to do.
Or we do it the other way around with #18757.
Doc update:
- [x] Update "Create a new Tails to store your backup" to use Tails Installer
- [x] Change "Create or update your backup" to be "Update your backup using the graphical utility"
issue