I am trying to add accessibility features in our AVPlayer to our apple TV app. (swift application)Our video content is hosted on a CDN. This CDN returns us a list of streams (mp4, flv, m3u8, etc) and a list of tracks for captions in a DFXP format.From the documentation that I am consulting, it seems that I'd need a master m3u8 that would host the captions file in order to display them, but our CDN doesn't seem to provide that option. Is there a way to add a captions file to an AVPlayerItem dynamically?