test(@angular-devkit/build-angular): workaround for rxjs 6 directory imports

rxjs 6 requires directory imports which are not support in ES modules. Disabling `fullySpecified` allows Webpack to ignore cases such as this until the package can be updated to use package exports.

Author: alan-agius4

packages/angular_devkit/build_webpack/test/angular-app/webpack.config.js

@@ -24,6 +24,10 @@ module.exports = {
   ],
   module: {
     rules: [
+      // rxjs 6 requires directory imports which are not support in ES modules.
+      // Disabling `fullySpecified` allows Webpack to ignore this but this is
+      // not ideal because it currently disables ESM behavior import for all JS files.
+      { test: /\.[m]?js$/, resolve: { fullySpecified: false } },
       { test: /\.css$/, type: 'asset/source' },
       { test: /\.html$/, type: 'asset/source' },
       { test: /\.ts$/, loader: '@ngtools/webpack' },

packages/angular_devkit/build_webpack/test/basic-app/webpack.config.js

@@ -3,6 +3,14 @@ const path = require('path');
 module.exports = {
   mode: 'development',
   entry: path.resolve(__dirname, './src/main.js'),
+  module: {
+    rules: [
+      // rxjs 6 requires directory imports which are not support in ES modules.
+      // Disabling `fullySpecified` allows Webpack to ignore this but this is
+      // not ideal because it currently disables ESM behavior import for all JS files.
+      { test: /\.[m]?js$/, resolve: { fullySpecified: false } },
+    ],
+  },
   output: {
     path: path.resolve(__dirname, './dist'),
     filename: 'bundle.js',