build(docs-infra): update project structure to cli@9 10/12 (tsconfig.json) (#36015)

Update `tsconfig[.*].json`.
Also, all make necessary changes to ensure the example apps can be
successfully built with the new, stricter type-checking options.

PR Close #36015

aio/content/examples/template-expression-operators/src/app/app.component.html

@@ -72,8 +72,8 @@
 <h2>Non-null assertion operator (<code>!</code>)</h2>
 <div>
   <!-- #docregion non-null -->
-  <!--No color, no error -->
-  <p *ngIf="item">The item's color is: {{item!.color}}</p>
+  <!-- Assert color is defined, even if according to the `Item` type it could be undefined. -->
+  <p>The item's color is: {{item.color!.toUpperCase()}}</p>
   <!-- #enddocregion non-null -->
 
 

aio/content/examples/template-expression-operators/src/app/app.component.ts

@@ -1,6 +1,13 @@
 import { Component } from '@angular/core';
 
 
+interface Item {
+  name: string;
+  manufactureDate: Date;
+  color?: string | null;
+  price: number;
+}
+
 @Component({
   selector: 'app-root',
   templateUrl: './app.component.html',
@@ -9,10 +16,11 @@ import { Component } from '@angular/core';
 export class AppComponent {
   title = 'Template Expression Operators';
 
-  item = {
+  item: Item = {
     name : 'Telephone',
     manufactureDate : new Date(1980, 1, 25),
-    price: 98
+    color: 'orange',
+    price: 98,
   };
 
   nullItem = null;