🛠 Repo: Enable eslint-plugin-n in ESLint config

[JoshuaKGoldberg]

Tooling Suggestion Checklist

• [X] I have tried restarting my IDE and the issue persists.
• [X] I have pulled the latest master branch of the repository.
• [X] I have read and agree to Mocha's Code of Conduct and Contributing Guidelines
• [X] I have searched for related issues and issues with the faq label, but none matched my issue.
• [X] I want to provide a PR to resolve this

Overview

eslint-plugin-node is a devDependency in package.json: https://github.com/mochajs/mocha/blob/645469e1920e2e86458ff068e74eef2e2915083e/package.json#L95

...but not used in the ESLint config.

The eslint-plugin-n plugin (the successor to eslint-plugin-node) is actually useful though. Let's enable from its recommended preset config?

Additional Info

The devDependency is being removed in #5060, but that's just because it's unused. This issue is suggesting adding it (well, eslint-plugin-n) back.