Pull out a PreferenceController of lock screen from accessibility

To reduce the complexity of AccessibilitySettings, we are planning to
create a bunch of preference controllers. First of all, we are converting
lock screen preference to a preference controller. The rest part will be
uploaded soon.

Bug: 135056871
Test: robotest, manual
Change-Id: I6079136f3d08934c9a5363eb4d0e0ade29f8ba99