feat: add comment injection

[thedadams]

If a user has the comment extension installed, then it will handle highlighting certain aspects of the comments like TODOs, FIXMEs, etc

[caius]

Oh neat, this looks like a good improvement to make.

Do you know what the behaviour is if the comment extension isn't installed please? I'm guessing it just hilights as a make comment without any syntax, but need to be sure it doesn't cause an error

[thedadams]

@caius Yes, that's correct: if the comment extension is not installed, then the comment is highlighted as a comment without error.

The similar change was merged for the languages bundled with Zed: zed-industries/zed#39884

[thedadams]

@caius Would you like to take another look at this? The comment extension is gaining a little traction.

[caius]

Ha, thanks for the nudge. Sounds good, thanks for updating!