Add TypeScript type-checking to all rules

[bmish]

We don't need to convert our JavaScript files to TypeScript, but by adding JSDoc comments with types and using the TypeScript checkJs option, we can get the benefits of type-checking. See this PR for an example and list of benefits: square/eslint-plugin-square#723.

We also want to export types for consumers.

[michaelfaith]

Would you been open to a full migration to TypeScript if someone contributed it? Or would you prefer js with doc comments?

[bmish]

I'm open to that -- a full migration to TypeScript is the end-goal. Jsdoc comments can just be a nice intermediary step to get there.

We would want to do this as a follow-up to the ESM migration which is already open:

• feat!: move to ESM only #516

[michaelfaith]

Great, i'd be down to help with that.

[bmish]

Here's another example of the intermediary jsdoc type-annotation conversion (even just this can turn into a huge PR):

• feat: add type-checking with jsdoc TypeScript types and publish types qunitjs/eslint-plugin-qunit#571

[michaelfaith]

Right on. If anyone wants to take a stab at that interim solution, feel free.

I've started on the full TypeScript migration here: main...michaelfaith:eslint-plugin-eslint-plugin:build/typescript I'm going rule by rule, and then will do the tests one-by-one. I've partially migrated the big utils module, but I'm just doing that as I migrate rules that use the functions.

I'll be going out of town next week, and so I won't make a ton more progress until I'm back.

[michaelfaith]

Update: I'm about halfway through migrating the rules. I'll do tests after that.

[michaelfaith]

Update: all of the runtime code has been migrated (rules, utils, and plugin). Migrating the tests are what's left. I'd certainly welcome any feedback you might have with what's done so far.

[michaelfaith]

The tests are going super fast, and most of them are just a pure rename with no other changes, which makes me feel good about them being a good validation that behavior hasn't changed. Since it is going to be a pretty large PR, once I've gotten the initial migration done, I'll look for smaller pieces I can peel off and PR separately ahead of the big PR, to help reduce it a bit.

[michaelfaith]

Supporting PR, moving the repo's eslint config to TypeScript (which is necessary to continue using the plugin locally once it's in typescript, without needing to build first) #531

[michaelfaith]

Another supporting PR, removing the (now unnecessary) context compatibility functions. I should have removed those when dropping support for ESLint v8. And I did it in the TS branch, but that already is going to have a ton of changes. So, breaking this out separately. #532