fix(aio): correctly reload page to apply ServiceWorker update (#16170)

Previously, due ot a limitation/bug in AoT compilation and `useValue`, the
`global` injected into `SwUpdateNotificationsService` was always undefined,
which prevented it from actually reloading the page after activating a
ServiceWorker update.

This commit fixes it by switching to `useFactory`, which works correctly with
AoT.

aio/src/app/sw-updates/global.value.spec.ts

@@ -0,0 +1,18 @@
+import { ReflectiveInjector } from '@angular/core';
+
+import { Global, globalProvider } from './global.value';
+
+
+describe('Global', () => {
+  let value: any;
+
+  beforeEach(() => {
+    const injector = ReflectiveInjector.resolveAndCreate([globalProvider]);
+    value = injector.get(Global);
+  });
+
+
+  it('should be `window`', () => {
+    expect(value).toBe(window);
+  });
+});

aio/src/app/sw-updates/global.value.ts

@@ -2,4 +2,7 @@ import { InjectionToken } from '@angular/core';
 
 
 export const Global = new InjectionToken<Window>('global');
-export const globalProvider = { provide: Global, useValue: window };
+export const globalProvider = { provide: Global, useFactory: globalFactory };
+export function globalFactory() {
+  return window;
+}