Add uniform event tracking to DeskClockGoogle

DeskClock has now been littered with calls of the form:
Events.sendEvent(category, action, label);

DeskClockApplication handles these events by logging them with a
uniform log tag.

Category is one of: Alarm, Clock, Timer, Stopwatch
Action describes what happened: e.g. create, delete, snooze, dismiss, etc.
Label describes where the action originated: DeskClock, Notification,
Wear, Intent, Voice

Bug: 20038553
Change-Id: Ia2485582e9da9e37a6858db3b61a68c9102c778d