feat(rome_js_analyze): no unused starting with underscore; small hack for React and removing suggested fix

[xunilrj]

Summary

This improves noUnusedVariables in three ways and removes the suggestion of removing the unused variables:

1 - It does not flag variables starting with "_";
2 - It does not flag React because some old codebases import React and use it only after JSX transpiling;
3 - It ignores function and class expressions (we are going to deal with these in another rule);

The suggestion was removed, because it suggested removing the first parameter of a function, and of course, completely changing the meaning of the other parameters. We need to think a little bit about what we want to suggest.

Test Plan

> cargo test -p rome_js_analuze -- no_unused

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[ematipico]

@xunilrj once this PR is merged, could you please add a comment to #2991, and remind to update the documentation of the rule with these two gotchas? - the exemption of React, and variables that start with underscore.

[Boshen]

FYI for parameters, eslint has the after-used option, which I think is pretty nice for a default.

after-used - unused positional arguments that occur before the last used argument will not be checked, but all named arguments and all positional arguments after the last used argument will be checked.

https://eslint.org/docs/latest/rules/no-unused-vars#args

[leops]

I think we could still keep the code action for variables, but instead of removing the whole declaration it could suggest to prefix the name with an underscore ?

[xunilrj]

I would prefer to remove it for now. And we can return it after it is a little bit more mature.

[leops]

The check for React should only apply to JSX files, although at the moment I don't think we have access to the SourceType for the file in the RuleContext

[ematipico]

To add more, we were discussing about implementing JSX parsing to JS files. If that happens in the future, we would need access to that information too.

[xunilrj]

No, we don´t.
It is a little bit hacky now. I expect this to be turned into an option in the future.

[xunilrj]

FYI for parameters, eslint has the after-used option, which I think is pretty nice for a default.

after-used - unused positional arguments that occur before the last used argument will not be checked, but all named arguments and all positional arguments after the last used argument will be checked.

https://eslint.org/docs/latest/rules/no-unused-vars#args

hum... Honestly not sure about this. One of the reasons I like noUnusedVariables is to get typos. So, for example, the code below would not flag req as unused.

Now... today we only have two ways to suppress these:

1 - Suppression lines;
2 - Starting with an underscore.

Are these fine and enough?

const server = http.createServer(function(req, res) {
    console.log(re); //try to use req but typo
    console.log(res); // correctly uses res
});