InCallUI: Add initial smart cover support

Change-Id: I7bd476a725efff9a3b9cfce91771750e231ea50f
Signed-off-by: Roman Birg <roman@cyngn.com>

Conflicts:
	src/com/android/incallui/InCallActivity.java
InCallUI: fix smartcover always showing  answer fragment

It seems the deleted lines were causing the issue as InCallUI properly handles logic for
showing and hiding the fragment itself.

Change-Id: I1d45b49ae48931adf48faa555296a467373e9247
Signed-off-by: Roman Birg <roman@cyngn.com>