Confirm when starting without unlocking the Persistent Storage

During the usability tests of the Additional Software beta, 3 participants out of 5 missed the new field to unlock the “Encrypted Persistent Storage” when restarting with a persistent storage for the first time:

• 2 of them restarted without seeing it.
• 1 of them saw it right before restarting.

They would probably easily learn from their mistake for the next time. Still, P4 missed it a second time :)

During the trainings in Brazil (#19103 (closed)), several people missed the new option to unlock the Persistent Storage when restarting and had to be taught how to do it. The English interface probably didn't help either. (#5501)

If we assume that people who have a persistent storage want to unlock it in the vast majority of cases, it could be worth asking for confirmation before starting without unlocking the persistent storage in case one is detected.

That might save some of our users a bunch of restarts.

• Remove links to "first_steps/persistence#use"? (unless we don't add this confirmation to the Welcome Screen)