Move nodejs backend to ESM

[AdityaHegde]

We have a mix of esm and commonjs in our code right now. Nodejs code transpiles to commonjs. This leads to issues with shared package.json.

With nodejs on esm we can move to using transpiled files in our tests to speed them up. Also makes it easy to avoid issues around changing type in package.json.

One caveat is that vercel/pkg doesnt support it just yet. For those builds jobs we still need to transpile to commonjs.