feat!: migrate to ESM

[mdonnalley]

BREAKING CHANGES: ESM and node 18 minimum

[git2gus]

This issue has been linked to a new work item: W-14284915

[mshanemc]

QA using the published 6.0.1 in sf

nightly:
✅ help (an sf command with colons)
✅ help (a command from a very old 3PP plugin, colons)
stable:
✅ help (an sf command with colons)
✅ help (an sf command with space)
✅ help (an sf JIT command with spaces)
✅ help (a command from a very old 3PP plugin, colons)
✅ help (a command from a very old 3PP plugin, spaces)