Update FFMPEG driver to support H265/HEVC

[Cardy2]

OSH H265 video data doesn't contain the needed parameter sets (VPS/SPS/PPS extracted from Hvcc extradata) to decode H265 video in the viewer or any downstream client.

Add a method to get the HVCC annexB extradata so that it is included downstream

[Cardy2]

PR has been opened with testing guidelines. @kyle-fitzp reviewed the code and said it looked good and video worked using the transcoder to view