fix(angular): NavController works with nested outlets (#28421)

Issue number: resolves #28417

---------

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issue. -->

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## What is the current behavior?
<!-- Please describe the current behavior that you are modifying. -->

The common `IonRouterOutlet` was trying to inject another common
`IonRouterOutlet` into `parentOutlet`:
dc94ae01fe/packages/angular/common/src/directives/navigation/router-outlet.ts (L119)
None existed, so this field was `null`.

This is a problem if developers are using the module `IonRouterOutlet`
since parent router outlets will not be currently injected because
Angular is trying to use the common `IonRouterOutlet` not the module
`IonRouterOutlet`:
https://github.com/ionic-team/ionic-framework/blob/main/packages/angular/src/directives/navigation/ion-router-outlet.ts.
The same goes for the standalone `IonRouterOutlet`.

This resulted in things such as `NavController.pop` not working in
nested outlets because the parentOutlet was not defined.

## What is the new behavior?
<!-- Please describe the behavior or changes that are being added by
this PR. -->

- `IonRouterOutlet` now injects the correct router outlet instance for
`parentOutlet`

## Does this introduce a breaking change?

- [ ] Yes
- [x] No

<!-- If this introduces a breaking change, please describe the impact
and migration path for existing applications below. -->


## Other information

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screenshots of how the component looks before and after the change. -->

Dev build: `7.5.3-dev.11698328998.1a79f815`

packages/angular/test/base/src/app/lazy/nested-outlet-page/nested-outlet-page.component.html

@@ -4,4 +4,7 @@
     <ion-button routerLink="/lazy/tabs" id="goto-tabs">Go To Tabs</ion-button>
     <ion-button routerLink="/lazy/nested-outlet/page2" id="goto-nested-page2">Go To SECOND</ion-button>
   </p>
+  <p id="parent-outlet">
+    Has Parent Outlet: <span>{{ hasParentOutlet }}</span>
+  </p>
 </ion-content>

packages/angular/test/base/src/app/lazy/nested-outlet-page/nested-outlet-page.component.ts

@@ -1,10 +1,16 @@
 import { Component, NgZone, OnDestroy, OnInit } from '@angular/core';
+import { IonRouterOutlet } from '@ionic/angular';
 
 @Component({
   selector: 'app-nested-outlet-page',
   templateUrl: './nested-outlet-page.component.html',
 })
 export class NestedOutletPageComponent implements OnDestroy, OnInit {
+  hasParentOutlet = false;
+
+  constructor(private routerOutlet: IonRouterOutlet) {
+    this.hasParentOutlet = routerOutlet.parentOutlet != null;
+  }
 
   ngOnInit() {
     NgZone.assertInAngularZone();

packages/angular/test/base/src/app/standalone/tabs/tab1.component.ts

@@ -1,12 +1,21 @@
 import { Component } from '@angular/core';
+import { IonRouterOutlet } from '@ionic/angular/standalone';
 
 @Component({
   selector: 'app-tab-one',
   template: `
     Tab 1
+
+    <p id="parent-outlet">
+      Has Parent Outlet: <span>{{ hasParentOutlet }}</span>
+    </p>
   `,
   standalone: true,
 })
 export class TabOneComponent {
+  hasParentOutlet = false;
 
+  constructor(private routerOutlet: IonRouterOutlet) {
+    this.hasParentOutlet = routerOutlet.parentOutlet != null;
+  }
 }