Integrate outstanding 608 PR

There are outstanding PRs that did not make it into our 608 implementation. These changes need to be added to CML:

https://github.com/Dash-Industry-Forum/cea608.js/pull/3
https://github.com/Dash-Industry-Forum/dash.js/pull/3719
https://github.com/video-dev/hls.js/pull/5557
https://github.com/video-dev/hls.js/issues/6427


