Keep RemoteInputView visible when focused

Scrolls the NotificationStackScrollLayout in response to movement
to ensure that the focused view stays visible. Also makes sure that
the action list is always aligned at the bottom of the notification
to avoid jank during this scrolling when the height changes.

Fixes: 28193862
Fixes: 26919632
Change-Id: I911a873367fe26eafd9fae4bca4e693d0827eba7