Settings: Add user protection and pie/navbar...

…toggle to SlimActions

Keep the user save and do not allow to disable all navigations to keep
the device usable. User will be notified

In Settings user get the choice to enable the other navigation method.
Of course
only on navbar devices due that hw key devices always have a working
navigation

and a small duplicate cleanup

Change-Id: I2528da3e87b149f01d8f2a7666b3f4fb9237effc