Use pure ES modules

See background at https://github.com/netlify/team-dev/issues/36

Once https://github.com/netlify/framework-info/issues/450 is done and released, we should use pure ES modules and make a major release.

This is more than just switching from CommonJS to import/export. See this list for other changes which might be involved. This should be broken in many PRs, as much as possible, to lower the risk. Also, non-breaking changes (such as adding file extensions in imports, or loading JSON files differently) should be done before the breaking changes (such as using import/export statements).

At the moment, framework-info is only used by:

• build-info: so support for pure ES modules should be added first there: https://github.com/netlify/build-info/issues/181
• netlify-cli: same thing for Netlify CLI: https://github.com/netlify/cli/issues/3514
• netlify-react-ui: will this be a problem when importing this module from netlify-react-ui? Do we bundle code to make ES modules work in netlify-react-ui? Or maybe we now only support browsers with ES modules support? @nasivuela Do you know what the situation is?

[ehmicky]

Done!

[nasivuela]

To be clear, I’m not contemplating using ESM directly on the browser at the moment, just wondering if our current setup will bundle an ESM package.