docs: Dependency Injection guides for CLI (#19892)

PR Close #19892

aio/content/examples/dependency-injection/src/app/dummy.module.ts

@@ -0,0 +1,25 @@
+
+/// Dummy modules to satisfy Angular Language Service
+import { NgModule } from '@angular/core';
+import { CommonModule } from '@angular/common';
+import { AppModule } from './app.module';
+
+////////
+
+import { AppComponent as AppComponent1 } from './app.component.1';
+
+@NgModule({
+  imports: [ CommonModule, AppModule ],
+  declarations: [ AppComponent1 ]
+})
+export class DummyModule1 {}
+
+/////////
+
+import { AppComponent as AppComponent2 } from './app.component.2';
+
+@NgModule({
+  imports: [ CommonModule, AppModule ],
+  declarations: [ AppComponent2 ]
+})
+export class DummyModule2 {}