CJS → ESM

Technical Design

Create a wrapper migration to orchestrate individual sub-migrations (eg inline require()s → await import() or import.sync() depending on parent context being sync or async).

This wrapper should handle:

1. Running individual API migrations
2. Update files using CJS-specific extension (.cjs → .mjs, etc).
3. Update package.json ("type": "commonjs" → "type": "module", etc).

I think we can release a 0.1.0 version with a subset:

• https://github.com/nodejs/userland-migrations/issues/342 (without the file extension changer)
• https://github.com/nodejs/userland-migrations/issues/344
• Complete API migrations for
  • https://github.com/nodejs/userland-migrations/issues/345
  • https://github.com/nodejs/userland-migrations/issues/349
  • https://github.com/nodejs/userland-migrations/issues/349
  • https://github.com/nodejs/userland-migrations/issues/350
• Incomplete API migrations with detection + logging for all other API migrations

[!IMPORTANT]
Each sub-task should have its own PR