Show which modules support ES modules

Hey 👋,

Webpack and other bundlers support a module option for ES modules for tree shaking. It would be nice to see which modules have support for it. Maybe even show which modules have support for sideEffects.

See https://webpack.js.org/guides/tree-shaking/#mark-the-file-as-side-effect-free and https://webpack.js.org/configuration/resolve/#resolve-mainfields.