feat: plugin loader

[arendjr]

Summary

Continuation of #4071

Note this doesn't integrate the plugins into the analyzer yet, like the previous one did. This just makes sure they load as we want them to.

Test Plan

Tests added. CI should remain green.

[codspeed-hq]

CodSpeed Performance Report

Merging #4234 will degrade performances by 7.31%

_{Comparing arendjr:plugin-loader (9a3d4a5) with next (f557e5c)}

Summary

❌ 4 regressions
✅ 99 untouched benchmarks

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

	Benchmark	next	arendjr:plugin-loader	Change
❌	pure_9395922602181450299.css[cached]	3.4 ms	3.6 ms	-6.12%
❌	router_17129688031671448157.ts[cached]	2.1 ms	2.2 ms	-6.05%
❌	db_17847247775464589309.json[cached]	13.1 ms	14 ms	-6.3%
❌	db_17847247775464589309.json[uncached]	15.4 ms	16.6 ms	-7.31%

[ematipico]

Should we change the destination of the PR to next?

[arendjr]

I've rebased onto next. I've also included the Grit upgrade, because it wouldn't cleanly apply otherwise.

[arendjr]

Btw, thinking of the whole manifest thing, while I like this approach for future compatibility and the ability to publish plugins, I think I’ll still implement the ability to refer to refer to Grit files directly from the plugins array. It should be easy enough for us to detect and then instantiate a single-rule plugin and it’ll greatly simplify the use case when someone wants to have one or a few rules in their own repository.

[ematipico]

I think the PR should be rebased because there are changes that don't belong here

[ematipico]

It's possible you created the crate manually or with cargo. If so you, you need to update manually knope.toml and add the crate. We have just new-crate that updates the file automatically

[arendjr]

Done

[ematipico]

Documentation is missing: the trait and the function.

[ematipico]

I think these snapshots could be improved by providing the input/files provided.