package output as `esm` + `cjs`

[ivanhofer]

I need this package in an esm context so I took the time to convert it. There weren't that many things to change, so the process was straigt forward.

• The build script now outputs cjs and esm code. In order to make the code run in an esm context without setting "type": "module" inside package.json all generated esm files need to end with the .mjs file extension. Therefor the fix-esm-output.js script is needed.
• All imports were altered using the "node16" module resolution.
• All require statements are rewritten using import statements. This did remove the "lazy-import" behavior as dynamic import statements must use async-await. But the only place where this affects regular runtime code is where esprima get's used. But since it is a regular dependency of recast nothing should fail.
• Tests were left unchanged and still run sucessfully for the cjs output.

I hope this could be merged into the main project so I don't have to maintain a copy of it. Let me know if there are still some things missing.

[benmccann]

Unfortunately Ivan passed away while competing during a race: https://github.com/ivanhofer/typesafe-i18n/issues/739

I still get a bit sad everytime I come across a PR from him. You will be missed Ivan.

I thought I'd make a note of it here as it's likely you may be unaware and this PR has some merge conflicts that will never be addressed by the original author.

[eventualbuddha]

@benmccann I’m so sorry to hear that. Thank you for notifying us. I’ll close this PR, but I hope someone else may base their future work on top of it.