🚀 Feature: Find or create a lint rule that enforces exported types

[JoshuaKGoldberg]

Bug Report Checklist

• I have tried restarting my IDE and the issue persists.
• I have pulled the latest main branch of the repository.
• I have searched for related issues and found none that matched my issue.

Overview

I see code like this a lot:

interface SomeSettings {
  something: string;
}

export function something(settings: SomeSettings) {
  // ...
}

IMO if an interface/type is used by something that's exported, it'd be good to export SomeSettings. That way if future folks want to use it, they won't have issues trying to import it.

Additional Info

Similar issue here: webpro-nl/knip#127.

I think part of this work should be:

1. Seeing if it already exists in https://github.com/typescript-eslint/typescript-eslint/issues
   • If it doesn't yet exist, filing a proper issue there I filed it: Rule proposal: Export all types used in exports typescript-eslint/typescript-eslint#7670
2. Waiting until that issue is either accepted or declined
   • If it's accepted, merging the PR into typescript-eslint
   • If it's declined, either making the rule in an existing community plugin (I don't know which if any would be a good place) or making a new plugin with the rule