Long-press gesture for lock screen affordances.

If the flag for customizable lock screen quick affordances is
enabled, the required geture to activate a lock screen quick affordance
is now a standard long press instead of a click.

Fix: 254857466
Test: long-pressing the button causes it to scale-animate and then
activate. A "tap" sound plays when it activates. Moving the finger too
far off the touch target while holding down cancels the gesture.
Releasing the finger too quickly causes the view to shake-animate and a
corrective message to appear in the indication area.

Change-Id: I130169d6dcdb6779bb914b0a3c0d3b0fc522567d