Show IMS Conference StatusHints in InCall.

A lot of this logic for figuring out what label should be shown seems
like it should be determined in the presenter, rather than passing
through all this information to the fragment, but it can be cleaned up
at another time.

+ minor layout tweak.

Bug: 20181703
Change-Id: I392ce7cffc8c05eb94859892e899ce7c693895aa