[FRP] Theming for Pattern and Password screens

Basic theming for pattern and password screens. Create subclasses for
ChooseLockPassword and ChooseLockPattern, and copied their XML
layouts.

This CL mainly uses the buttons in the original screens as-is, with a
follow-up CL coming to change to use the nav bar buttons.

Bug: 18482708
Change-Id: I81751f781de633aff23fc68657589360007c235a