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