Watch extra_syntaxes for changes in serve


I was about to create a PR to add the ability to watch the directories in extra_syntaxes for changes, and rebuild the site.

The diff is here:

I removed most of the logic in detect_change_kind.
I moved the ChangeKind in the watch_this Vec, that now contains a tuple of path, ChangeKind, and WatchMode.
I remove the test can_detect_change_kind, because I don’t think it’s relevant anymore
I couldn’t run the tests cmd::init::tests::strip_unc_required_test and cmd::init::tests::strip_unc_test, because they expect the user to be VssAdministrator

What do you think about it?

I think it’s a bit too niche to be added to be honest. The amount of people using extra_syntaxes is already very very low so I would avoid adding more code for it