Replace JSONPath with jq in jsondocck

[fluiderson]

This is an ongoing effort to close #142479. I've decided to take a hard path and rewrite rustdoc-types's entire testsuite. I don't think it'll be a good idea to construct a JSONPath-jq transpiler because it'll look really awkward for new contributors, JSONPath's limitations + jaq's own quirks may create a lot of questions that even current maintainers would've no answers for without digging into jsondocck's internals.

I expect jsondocck to have just 2 directives: jq and arg. Thanks to jq's flexibility, these 2 can do everything that the current directive set can and much more (actually, too much, I left some comments to opt out some dependencies when it'll be possible on jaq's side). I'm trying to actively utilize jq's features instead of just blindly rewriting existing assertions, so there should be more deletions than additions.

When I'll be done, I'll try to rebase and split my work to make it more easier to review. So far jsondocck is already functional, so you can check out how it may look like and give some feedback if you want. I'll commit updated tests folder by folder.

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[bors]

☔ The latest upstream changes (presumably #143337) made this pull request unmergeable. Please resolve the merge conflicts.

[fmease]

(cc @aDotInTheVoid)

[aDotInTheVoid]

Sorry for taking so long to review this. Thanks for working on it, especially the repetitive test migration.

I don't think it'll be a good idea to construct a JSONPath-jq transpiler because it'll look really awkward for new contributors

What do you mean by this? The idea was to use the transpiler to migrate all the assertions in the tests, leaving them in jq. New contributors should never need to know it existed.

I expect jsondocck to have just 2 directives: jq and arg

I think this is a quite bad idea. It means we loose any sort of good error reporting. With this PR at the moment, we can only say that a check failed, but not why (in the case that the query matched the wrong value). Having this is really important I think.