Converts a Spatial Video (recorded from iOS) to a side-by-side stereo video
Video Writing code is based on
https://gist.github.com/xaphod/de83379cc982108a5b38115957a247f9
Info on how to read a spacial video into left and right eye images is based from:
https://www.finnvoorhees.com/words/reading-and-writing-spatial-video-with-avfoundation