Rollup merge of rust-lang#142924 - lolbinarycat:tidy-js-extra-checks, r=Kobzol

tidy: move rustdoc js stuff into a tidy extra check

Most of these were factored out of CI scripts, but `eslint` in particular was previously implemented with its own special cased logic.

A new option has been added to bootstrap, `build.tidy-extra-checks`, which serves as a default value for the `--extra-checks` flag.  This is mostly for the benefit of rustdoc js maintainers, but should also help bootstrap py maintainers.

Additionally, `--extra-checks=cpp` has been documented.

I'm not super happy with how long the extra check names are in comparison to the others (in particular `typecheck`), but I couldn't think of anything better (I didn't want to name it `tsc` on the off chance we want to switch to a different typechecking engine in the future).

It would be nice to convert the extra checks arg into a proper enum, both for warning on unknown values and to provide better shell completion.

r? ``@GuillaumeGomez``

Fixes: rust-lang#144093

Author: matthiaskrgr

.gitignore

@@ -85,8 +85,6 @@ __pycache__/
 
 ## Node
 node_modules
-package-lock.json
-package.json
 /src/doc/rustc-dev-guide/mermaid.min.js
 
 ## Rustdoc GUI tests

REUSE.toml

@@ -37,6 +37,8 @@ path = [
     "rust-bors.toml",
     "triagebot.toml",
     "typos.toml",
+    "package.json",
+    "package-lock.json",
     "x",
     "x.ps1",
     "x.py",