eslint v9 support

[mozfreddyb]

Since this seems like a common question.

I started working on it, but it looks like there's a conflict with our dependencies: I think we'll need to wait until typescript-eslint releases a version that supports eslint 9.

This is unless someone can help me figure out a way to support eslint >=9 with optional typescript and eslint <9 with full typescript support

[nicolo-ribaudo]

typescript-eslint published today their timeline for it: https://typescript-eslint.io/blog/announcing-typescript-eslint-v8-beta/