Fix issue where secondary call info overlaps video preview.

Other issues:
- Secondary caller info should not be shown when in fullscreen mode.

Solution:
- Added onSecondaryCallerInfoVisibilityChanged to InCallEventListener (
which is documented as a place for events between fragments).
- In CallCard fragment, call notify listeners of this callback of the
state change.
- In VideoCallPresenter/Fragment, handle changes to the visibility of the
secondary caller info box to shift the preview surface up or down.
- Added hide/show animation for the secondary caller info when entering
and exiting fullscreen mode.

Bug: 20914754
Change-Id: I44ae0e94e214892776487bff4cc09be8c5640db1