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

PS:
- added Jubas suggestions

- This commit have some exclusions ond chages to fit crDroid sources made by @cristianomatos
Original commit: https://github.com/SlimRoms/packages_apps_Settings/commit/30482e059fb55b9d3aa4d461a0715d77ec70776a

Change-Id: I2528da3e87b149f01d8f2a7666b3f4fb9237effc