have a consistent path to persistence root
Originally created by Tails on #5854 (Redmine)
Already two features of the persistence are pointing the user to the root of the persistent volume ("Dotfiles" and "Additional software"). It would be quite useful to have a uniform path to access this folder instead of being dependent on the device name.
For example could there be a symbolic link to /lib/live/mount/persistence/XXX_unlocked/ named /lib/live/mount/persistence/root/?