AmbientIndication: Add tap again hint

Adds a hint for tapping the ambient indication again to open.
Also fixes an issue where the indication bottom padding was not correctly
updated if the indication was shown while the panel is collapsed.

Bug: 38387500
Test: tap indication, verify it shows the tap-again-to-open hint. Also verify that if the indication gets set while the phone is unlocked that sufficient space is reserved after transitioning to the lockscreen.
Change-Id: Ie9a152b0bd86807958376fd278ef9502c03af6b2