The new script makes sure that strings files don't contain obsolete
strings but also ease the job of contributors by adding missing
translations as comments.
A Github Action ensures that translations stay in sync over time.
Bring back the "Vibration" option.
The duration option isn't added back because the vibration settings are
still handled by Android. In fact, the option has no effect if the
vibration are disabled in the system settings.
This partially reverts commit ef03dfed5c.
