chord: add two-key rule to trigger wear screenshot

- Register a TwoKeyCombinationRule to fire an intent to
  WearScreenshotReceiver to trigger wear screenshot logic.

Note: this is still using existing two-key rule logic where short/long
press are not differentiated for the same chord. See ag/20841280 for
potential logic change.

BUG: 262445007
Change-Id: Ibf57fcea24dacdabb5346db64bb3644676463069
(cherry picked from commit c0b18c2ad82b733a5441696a8657df7b7c8136c9)