Video rotation data should be extracted with ffmpeg-next

[blissd]

Videos contain rotation data (similar to the orientation stored in photo EXIF data) which is extracted and processed by Fotema so videos are displayed the right way up. However, to extract the rotation data I've used the ffprobe CLI tool which must be launched by Fotema for each video that is process because I couldn't figure out how to extract the data with ffmpeg-next.

This is slow and I would like the code for extracting the rotation to be rewritten to use the ffmpeg-next API, just like the other metadata that is extracted.