ControllerInterface/Android: Rip out ButtonManager

ButtonManager is very different from how a normal input backend works,
and is making it hard for us to improve controller support on Android.
The following commits will add a new input backend in its place.

Source/Core/InputCommon/ControllerInterface/Android/Android.h

@@ -5,7 +5,5 @@
 
 namespace ciface::Android
 {
-void SetMotionSensorsEnabled(bool accelerometer_enabled, bool gyroscope_enabled);
-
 void PopulateDevices();
 }  // namespace ciface::Android