Show error dialogs in InCallUI

* Show InCallActivity for state IN_CALL as well to ensure that
error dialogs are shown
* Override pending transitions in CircularRevealActivity
to avoid animation jank when starting new call from launcher
* Don't override disconnect cause in onCallRemoved
* Track service unbinding and binding in InCallPresenter. An
unbound service means InCallActivity will not be shown.

Bug: 18675781

Change-Id: I6a34091dba13c730e5b69bfef50c2dda8224803a