The dark theme screen has been removed in favor of a simple
toggle with a dialog that shows up the first time a user
tries to enable dark theme when in light theme.
Test: robotests pass
Bug: 130251804
Change-Id: I48f8e24a2b2a117e5a8054c5bc0b240ba68fe1ad
The dark theme preference should have it's own screen rather than
being a dialog. This adds some boilerplate code that will be
needed for the illustration as well as converting the current
list preference to open a new screen.
Test: robotests
Bug: 128686189
Change-Id: I5b62276353c0d39ad2ad00d21d2280e76cceb09b
Having consistent import order will reduce chance of merge
conflict between internal and external master
Test: rebuild
Change-Id: I0b1a170967ddcce7f388603fd521f6ed1eeba30b
