This allows us to drive sequencer time from arbitrary external sources such as media players or other clocks.
Added a new media component which owns a media player and texture, such that media players can work nicely with multiplayer PIE
Added a new media track that can play back media sources on any UMediaPlayer* property - primitive for the time being (only looping is supported, no start time offset etc). This track is currently written to support real-time playback rather than offline, frame-accurate playback
#rb Max.Chen, Matt.Hoffman
#ROBOMERGE-SOURCE: CL 10940608 via CL 10940611
#ROBOMERGE-BOT: (v632-10940481)
[CL 10940614 by andrew rodham in Main branch]