Enhance TestConnectionService to support 1-way video calls.

- added support for receiving 1-way video calls; this is useful when
testing receiving calls from a different device that does support 1-way
video calls and we want to ensure our implementation handles it.
- also add "capability_video_calling_relies_on_presence"

Change-Id: I417cd439aa8d6bebb5c35ec18fe5f5592535551c