Make multi presses on power button timeout configurable through overlay.

Previous implementation used the same timeout value as screen double tap which
does not take into account device specific hardware differences.
New implementation uses the existing ViewConfiguration#getMultiPressTimeout()
value which is configurable through a Setting item and default overlay.

Bug: 37671926
Test: Cherry-picked back to cw-f-dev, flashed on Sculpin with no
      configuration changed and verified that timeout was still at
      300ms. Added an overlay to increase the timeout, flashed on
      Sculpin and verified that the new timeout was being used.

Change-Id: Ie0ab705cafb2a3be9a31e66a03a3c9c656196ca1