Persistence preset: time zone
In #15548 (closed), we made it possible for the user to set a correct time by setting their local time and time zone.
In #6284 (closed), we made it so the local time is displayed in the top navigation bar instead of the GMT time.
On top of this, we should allow storing this time zone in the Persistent Storage to avoid having people configure it each time.
From https://gitlab.tails.boum.org/tails/blueprints/-/wikis/network_connection#ux-design: