[Base] long press back to kill with configurable timeout (1/2)

1 - 2 seconds (default)
2 - 1,5 seconds
3 - 1 second
4 - 0,5 second

PS: ONLY IN NAVIGATION BAR LONG PRESS BACK. STILL NEEDS TO BE IMPLEMENTED IN PIE

Change-Id: Id8ae04fc9ccd32aae64f8e1772b30a81bea2482c