Replace the device-specific functions with a class. Move some of the
key handling (for log visibility toggling and rebooting) into the UI
class. Fix up the key handling so there is less crosstalk between the
immediate keys and the queued keys (an increasing annoyance on
button-limited devices).
Change-Id: I698f6fd21c67a1e55429312a0484b6c393cad46f
Move all the functions in ui.c to be members of a ScreenRecoveryUI
class, which is a subclass of an abstract RecoveryUI class. Recovery
then creates a global singleton instance of this class and then invoke
the methods to drive the UI. We use this to allow substitution of a
different RecoveryUI implementation for devices with radically
different form factors (eg, that don't have a screen).
Change-Id: I76bdd34eca506149f4cc07685df6a4890473f3d9
