Exports all imported modules to browser requirejs via window.define.

This is specifically useful for Magento 2, which extensively uses requirejs.

Currently, a prefix of mixins! is added, so this is only usable with Magento 2.

In webpack.config.js:

const RequireJsExportPlugin = require('@sdinteractive/requirejs-export-plugin');

module.exports = {
  plugins: [
    new RequireJsExportPlugin(),
  ],
};

In Magento 2, this makes it so that requirejs code can load webpack modules (such as for UI components, etc.)

This also generates stubs for requirejs-loader, to allow for proper sequencing of the export.