Tapping clock on QS launches clock app

This change mimics the behavior in the alarm tile. Tapping on the clock
either:

- Launches the alarms tab of the Clock app using the ACTION_SHOW_ALARMS
  intent. OR
- Launches the intent of the last alarm that was sent to us via
  NextAlarmController

Test: manual
Test: ShadeHeaderControllerTest
Fixes: 259438579
Change-Id: I81e97a25f2a64c2f4cfc548b3bb7f2088a449d0e