Improve no plugin messages

[joyfulmantis]

This PR rewrites the way we check if a plugin is enabled for a request. This allows us to give more in-depth logging when we don't have any plugins that accept a request.

Things left to do for this PR

• Documentation
• Ensure edge cases work well

[michaelpj]

Okay, just getting to this. I'm unsure about the bouncing, tbh. I think it's probably just going to mask failures, which might be bad. What did you think about my suggestion here? I think we could do something similar for completions: use a key that's something like just the fully qualified name or something. Even if we had to do a mixed strategy (e.g. use the fully qualified name for non-local names, use a unique key for local names), that still means that we'd get resolve hits for e.g. all non-local names even if things are a bit stale.

Could we do the plugin error bit separately while we think about it?

[joyfulmantis]

Okay, just getting to this. I'm unsure about the bouncing, tbh. I think it's probably just going to mask failures, which might be bad. What did you think about my suggestion here? I think we could do something similar for completions: use a key that's something like just the fully qualified name or something. Even if we had to do a mixed strategy (e.g. use the fully qualified name for non-local names, use a unique key for local names), that still means that we'd get resolve hits for e.g. all non-local names even if things are a bit stale.

Could we do the plugin error bit separately while we think about it?

Okay sounds good, I'll dump the bounce stuff from this PR then, and we can revisit it later if we still need it.

[michaelpj]

I like the general direction, a few thoughts

[michaelpj]

This looks great now

[fendor]

LGTM!