HDR to SDR transcoding with tone map

By default HDR videos are transcoded into SDR, but resulting colors look washed out.

I [can](https://github.com/linkedin/LiTr/issues/252) transcode HDR videos into HDR, but such videos can't be correctly played on devices without HDR support, the colors will look washed out.

It would be great if LiTR supports tone mapping, it looks like it can be done using Open GL somehow. At least androidx.media3 transcoder [has a special flag](https://github.com/androidx/media/issues/304) for that. I don't want to use media3 library, its API is pretty bad and it lacks some features that I need (progress tracking, custom media sources support, etc). So it would really be great if LiTR could handle HDR to SDR transcoding.

Thanks for the library and your time :)

Start by reviewing the existing HDR transcoding discussion in issue #252 and the tone-mapping reference in androidx/media issue #304. No implementation files, tests, or entry points are identified in this issue. Done means LiTr can transcode HDR video to SDR with tone mapping so colors display correctly on devices without HDR support.

Written by the indexing model from the issue text.