This makes it so that static preferences can also be added after
the candidates so they can show up on the bottom of the screen.
This is done via a new xml tag for the preference screen that
is usually mostly empty that RaiodButtonPickerFragments use
Test: robotests
Bug: 111450127
Change-Id: I0fe2f480f0ff59b9bf9269e94b33ab4b008b47b8
