Lockscreen: option to allow status bar expand on secured lock screen
With logic to prohibit access to the quick settings.
Allows peeking on notifications even if lock screen is secured. If click
on notification launches activity user is prompted to unlock first.
This also makes ActiveScreen "expand notification panel" mode work on
secured lock screen.
QS: use more standard way of checking keyguard state
Makes QS locking work correctly with 3rd party lock screen apps.