fix(@angular-devkit/build-angular): shim node events builtin for dev server

The dev server requires a node 'events' builtin shim to function.  The dev server as written only currently works with package managers that hoist the `events` shim package to an accessible location.  Hoisting is unfortantely not standardized and the assumption within the dev server will not hold true for all package managers.

Closes angular#13680

Author: clydin

packages/angular_devkit/build_angular/src/dev-server/index.ts

@@ -149,6 +149,17 @@ export class DevServerBuilder implements Builder<DevServerBuilderOptions> {
         opnAddress = serverAddress + webpackDevServerConfig.publicPath;
         webpackConfig.devServer = webpackDevServerConfig;
 
+        // The dev server requires a node 'events' builtin shim to function.
+        // The dev server as written only currently works with package managers
+        // that hoist the `events` shim package to an accessible location.
+        // Hoisting is unfortantely not standardized and the assumption within
+        // the dev server will not hold true for all package managers.
+        if (!webpackConfig.node) {
+          webpackConfig.node = { events: true };
+        } else if (typeof webpackConfig.node === 'object') {
+          webpackConfig.node.events = true;
+        }
+
         return webpackDevServerBuilder.runWebpackDevServer(
           webpackConfig, undefined, getBrowserLoggingCb(browserOptions.verbose),
         );