ci: Add back the CLI integration test with pinning (#21555)

The CLI app is now checked in, rather than generated dynamically with
`ng new`. This loses some assertion power, but gains hermeticity.
It also checks in lock files for all integration tests, avoiding
floating version numbers.

We'll need another place to integration test between changes in
the various repositories - but the angular/angular PR-blocking status
is not the right place to do this.

PR Close #21555

integration/cli-hello-world/src/main.ts

@@ -0,0 +1,12 @@
+import { enableProdMode } from '@angular/core';
+import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
+
+import { AppModule } from './app/app.module';
+import { environment } from './environments/environment';
+
+if (environment.production) {
+  enableProdMode();
+}
+
+platformBrowserDynamic().bootstrapModule(AppModule)
+  .catch(err => console.log(err));