refactor(angular): alert controller uses correct core instance (#28538)

Issue number: Internal

---------

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## What is the current behavior?
As a takeaway from our learning session about a menuController bug in
Ionic Angular, the team would like to update our other providers to use
the same architecture as the menuController to prevent this kind of
issue from happening again in the future.

We also noticed that the common provider does not provide much value and
it's easier to just have two separate implementations in `src` and
`standalone`. (There wasn't much code we could de-duplicate)

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

- Removed the common alert provider in favor of separate ones in
src/standalone

## Does this introduce a breaking change?

- [ ] Yes
- [x] No

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and migration path for existing applications below. -->


## Other information

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

packages/angular/src/index.ts

@@ -20,7 +20,6 @@ export * from './directives/validators';
 
 // PROVIDERS
 export {
-  AlertController,
   LoadingController,
   DomController,
   NavController,
@@ -34,6 +33,7 @@ export {
   ViewDidEnter,
   ViewDidLeave,
 } from '@ionic/angular/common';
+export { AlertController } from './providers/alert-controller';
 export { AnimationController } from './providers/animation-controller';
 export { ActionSheetController } from './providers/action-sheet-controller';
 export { GestureController } from './providers/gesture-controller';

packages/angular/src/providers/alert-controller.ts

@@ -0,0 +1,13 @@
+import { Injectable } from '@angular/core';
+import { OverlayBaseController } from '@ionic/angular/common';
+import type { AlertOptions } from '@ionic/core';
+import { alertController } from '@ionic/core';
+
+@Injectable({
+  providedIn: 'root',
+})
+export class AlertController extends OverlayBaseController<AlertOptions, HTMLIonAlertElement> {
+  constructor() {
+    super(alertController);
+  }
+}