This reverts commits ef03dfed5c and
ff01678ba6.
The "vibration duration" slider is bought back.
The "vibration enabled" option is replaced by "custom vibration", which switch between the system haptic feedback or the custom vibration.
The slider is greyed when "custom vibration" is unchecked and is
allowed to have a value of 0 to disable vibrations within the app.
The intermediate values "light", "medium" and "strong" are removed and
no migration of the setting is made.
The newer haptic feedback API that is used instead of the vibrator
service since ef03dfe doesn't work for everyone.
The new vibration option allow to choose both the newer API ("system")
and the older API ("strong", "medium", "light").
