refactor(docs-infra): extract all `lazy-loading-ngmodules` examples from mini-app (#34599)

Previously, some of the examples in the `lazy-loading-ngmodules` guide
were hard-coded.

This commit ensures all examples in the guide are extracted from
docregions in the corresponding example project.

PR Close #34599

aio/content/examples/lazy-loading-ngmodules/src/app/app-routing.module.ts

@@ -4,23 +4,26 @@ import { NgModule } from '@angular/core';
 import { Routes, RouterModule } from '@angular/router';
 
 
-// #docregion const-routes
+// #docregion const-routes, routes-customers, routes-customers-orders
 const routes: Routes = [
   {
     path: 'customers',
     loadChildren: () => import('./customers/customers.module').then(mod => mod.CustomersModule)
+    // #enddocregion routes-customers
   },
   {
     path: 'orders',
     loadChildren: () => import('./orders/orders.module').then(mod => mod.OrdersModule)
+    // #enddocregion routes-customers-orders
   },
   {
     path: '',
     redirectTo: '',
     pathMatch: 'full'
+    // #docregion routes-customers, routes-customers-orders
   }
 ];
-// #enddocregion const-routes
+// #enddocregion const-routes, routes-customers, routes-customers-orders
 
 @NgModule({
   imports: [

aio/content/guide/lazy-loading-ngmodules.md

@@ -50,13 +50,10 @@ This creates a `customers` folder with the new lazy-loadable module `CustomersMo
 Because the new module is meant to be lazy-loaded, the command does NOT add a reference to the new feature module in the application's root module file, `app.module.ts`.
 Instead, it adds the declared route, `customers` to the `routes` array declared in the module provided as the `--module` option.
 
-<code-example language="typescript" header="src/app/app-routing.module.ts">
-const routes: Routes = [
-  {
-    path: 'customers',
-    loadChildren: () => import('./customers/customers.module').then(m => m.CustomersModule)
-  }
-];
+<code-example
+  header="src/app/app-routing.module.ts"
+  path="lazy-loading-ngmodules/src/app/app-routing.module.ts"
+  region="routes-customers">
 </code-example>
 
 Notice that the lazy-loading syntax uses `loadChildren` followed by a function that uses the browser's built-in `import('...')` syntax for dynamic imports.
@@ -73,17 +70,10 @@ ng generate module orders --route orders --module app.module
 This creates a new folder called `orders` containing the `OrdersModule` and `OrdersRoutingModule`, along with the new `OrdersComponent` source files.
 The `orders` route, specified with the `--route` option, is added to the `routes` array inside the `app-routing.module.ts` file, using the lazy-loading syntax.
 
-<code-example language="typescript" header="src/app/app-routing.module.ts">
-const routes: Routes = [
-  {
-    path: 'customers',
-    loadChildren: () => import('./customers/customers.module').then(m => m.CustomersModule)
-  },
-  {
-    path: 'orders',
-    loadChildren: () => import('./orders/orders.module').then(m => m.OrdersModule)
-  }
-];
+<code-example
+  header="src/app/app-routing.module.ts"
+  path="lazy-loading-ngmodules/src/app/app-routing.module.ts"
+  region="routes-customers-orders">
 </code-example>
 
 ## Set up the UI