🚀 Feature: Convert to pure ESM

[kirkwaiblinger]

Bug Report Checklist

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

Overview

require(ESM) is here. Let's only export ESM in the next major version (and set minimum node requirements accordingly)

Additional Info

No response

[JoshuaKGoldberg]

Strong 👍. This would make builds for package publishing much simpler...

Related draft PR: #760.