Controls - Add optional power menu layout

Begin to support additional power menu layout for controls. This moves
the global actions button to the top of window, and begins to add
support for a scrollable view. Very PoC. To enable:

adb shell settings put secure systemui.controls_available 1

Test: atest
Change-Id: Iaf493a6f3035db1a1859d94fb8a0487a1d4af8db