PasscodeLockController: Add proper 4 or 6 digits passcode support
This merge request is a follow up from !1244 (closed) adding:
- The ability of choosing to set a passcode of 4 or 6 digits
The update comes with:
- A fix of the passcode that is now properly set and is also properly matched with its length when the biometrics are not enabled
- The removal of useless and duplicated methods
- A bunch of cosmetics changes fixing the coding style and adding clarity to the file