Change sendSessionModifyRequest VideoProvider API signature.

Including a fromProfile in addition to the requestedProfile.

- Changed VideoCallImpl to generate the fromVideoProfile based on the
call's current videoState.  This ensures the InCall UI only needs to
pass in the new video profile; the VideoCall Impl already has enough
knowledge to generate the fromProfile.
  - Changed VideoCallImpl to track the current videoQuality, which forms
a part of the fromVideoProfile.

Bug: 20704229
Change-Id: I89f293f03a2b13fc8c1dcfd8a07ab8640d3950e0