add support for native es modules in Node

Description

Native ES modules were landed in node@12.7.0 (see proposal-pkg-exports).

I created small repo with interested for me packages like express, lodash, redux, redux-saga, etc - and try to run app in esm mode.

By default, there are many errors, but they easily fixed by npm run patch.

Some packages need to fix their source, but redux-saga packages need to fix only package.json. You can see example of fixes here - https://github.com/rifler/node-esm-example/blob/master/patches/packageJsonConfigs.js

[Andarist]

ESM is a dangerous thing that often cannot be shipped within the current major version of a library. Each library is different though so this should be carefully evaluated here - maybe there is a way to make CJS and ESM entrypoints coexist here but from my experience, there probably isn’t.

In a way, I would probably put this aside until React ships its ESM - cause this might be a final push for the React community to drop CJS and bump major versions everywhere.

[neurosnap]

Closing this issue because it’s unclear when we plan to support ESM because we want to maintain backwards compatibility.