Default emergency gesture setting On.

And a few drive-by fixes:
* Move all emergency gesture fragments and controllers to emergency
  package for better code colocation.
* Remove the placeholder video preference from emergency_gesture_settings.xml

Bug: 178009196
Test: reran robotests
Change-Id: Ifcb591e7ab8e5e5494c480cbbe9410c08c296f8e
12 files changed