[Sprint/QuietQuail](feat) Rich embed open in media modals #2162

Summary

Opening youtube videos in modals.

Testing

This has the potential to affect

My test plan (note gifs aren't working at present on sandboxes): Visit: https://feat-rich-embed-modals-2162.minds.io/richembedtest/

• Click through the content.
• Test in groups, comments and discovery>latest.
• Flip the feature flag via helm (any help, let me know).
• Refresh and check that everything still works

Try a variety of content.