craco: drop esnext rules

Since 08e59d2, shopify no longer published .esnext files for webpack
so we can drop these rules. However, when we do this, there is still
another .mjs issue that needs to be worked around.

craco.config.js

@@ -2,12 +2,7 @@
 //
 // https://github.com/gsoft-inc/craco/blob/master/packages/craco/README.md#configuration
 
-const {
-    addBeforeLoader,
-    getLoader,
-    getLoaders,
-    loaderByName,
-} = require('@craco/craco');
+const { addBeforeLoader, loaderByName } = require('@craco/craco');
 const CopyPlugin = require('copy-webpack-plugin');
 const LicensePlugin = require('license-webpack-plugin').LicenseWebpackPlugin;
 const MonacoWebpackPlugin = require('monaco-editor-webpack-plugin');
@@ -240,12 +235,6 @@ module.exports = {
                 filename: '[name].worker.[contenthash].js',
             }),
         ],
-        configure: {
-            resolve: {
-                // need 'esnext' first to avoid compile errors
-                mainFields: ['esnext', 'browser', 'module', 'main'],
-            },
-        },
     },
     plugins: [
         {
@@ -256,31 +245,13 @@ module.exports = {
                     pluginOptions,
                     context: { env, paths },
                 }) => {
-                    // add .esnext file extension for @shopify/*
-
-                    webpackConfig.resolve.extensions = [
-                        '.web.esnext',
-                        '.esnext',
-                        ...webpackConfig.resolve.extensions,
-                    ];
-
-                    const babelLoaders = getLoaders(
-                        webpackConfig,
-                        loaderByName('babel-loader'),
-                    );
-                    babelLoaders.matches[0].loader.test =
-                        /\.(esnext|js|mjs|jsx|ts|tsx)$/;
-                    babelLoaders.matches[1].loader.test = /\.(esnext|js|mjs)$/;
-
-                    const fileLoader = getLoader(
-                        webpackConfig,
-                        loaderByName('file-loader'),
-                    );
-                    fileLoader.match.loader.exclude = [
-                        /\.(esnext|js|mjs|jsx|ts|tsx)$/,
-                        /\.html$/,
-                        /\.json$/,
-                    ];
+                    // work around @shopify/* webpack compatibility
+                    // https://github.com/Shopify/quilt/issues/1722#issuecomment-789883471
+                    webpackConfig.module.rules.push({
+                        test: /\.mjs$/,
+                        include: /node_modules/,
+                        type: 'javascript/auto',
+                    });
 
                     // work around default handling of .wasm files
                     // https://github.com/webpack/webpack/issues/7352