Dismiss shade and keyguard for media buttons that launch an activity

It's possible for a media notification to include a button that opens an
app - like regular notifications, we should dismiss keyguard/shade so
the user sees the activity that was launched.

Bug: 209683600
Test: manual - verify dismissed in both locked and unlocked state

Change-Id: Ibfc232dea69457b9d21c6a2dfec708b8c9f39866