Remove compat_features from features already migrated to BCD tags

[queengooborg]

This PR removes the compat_features value from the features that have already had the BCD features list migrated to BCD tags.

Note: a number of features had comments about new BCD features to add after issues were resolved or nonreal values were removed. The comments have either been preserved or removed as needed, and updates to BCD have been performed as needed.

[ddbeck]

Did you do this by hand? 😬 I'm not super excited about doing this outside the context of #1672 since we'll be dumping a lot of rich trial cases for that kind of automation. We'll need to do this on a rolling basis (and I believe this is in you and @Elchi3's remit right now).

[queengooborg]

My thought process is to tackle the bulk by hand to start, so that by the time the automated process is ready to use, a lot less changes will be made at once which will let us catch any issues with the automatic process much easier. So, yes, this PR was done by hand, but I plan to work on automating this in the near future (probably will start after W3C TPAC)!

Doing it manually this first pass did help uncover a few issues that needed to be resolved, such as #1818, which an automated linter couldn't have resolved! 😆

[Elchi3]

Daniel and I discussed this today and we think it would be good to have a PR that is fully scripted and that stops if it encounters comments or other issues.

@queengooborg can you redo this for just the automated changes?

[Elchi3]

No answer. Closing.