fix(reorder-group): add children fallback for framework compatibility (#30593)

Issue number: resolves #30592

---------

## What is the current behavior?
Reorder group is failing for Angular, React & Vue due to the change from
`children` to `__children`.

## What is the new behavior?
- Fallback to `children` if `__children` is undefined.
- Adds an e2e test for Angular (depends on
https://github.com/ionic-team/ionic-framework/pull/30594)
- Tasks have been created to migrate and add e2e tests for the other
frameworks

## Does this introduce a breaking change?

- [ ] Yes
- [x] No

## Other information

Dev build: `8.7.2-dev.11754087334.1815cf22`

---------

Co-authored-by: Brandy Smith <6577830+brandyscarney@users.noreply.github.com>

packages/react/test/base/src/App.tsx

@@ -36,6 +36,7 @@ import IonPopoverNested from './pages/overlay-components/IonPopoverNested';
 import KeepContentsMounted from './pages/overlay-components/KeepContentsMounted';
 import OverlayComponents from './pages/overlay-components/OverlayComponents';
 import OverlayHooks from './pages/overlay-hooks/OverlayHooks';
+import ReorderGroup from './pages/ReorderGroup';
 
 setupIonicReact();
 
@@ -67,6 +68,7 @@ const App: React.FC = () => (
         <Route path="/tabs-direct-navigation" component={TabsDirectNavigation} />
         <Route path="/icons" component={Icons} />
         <Route path="/inputs" component={Inputs} />
+        <Route path="/reorder-group" component={ReorderGroup} />
       </IonRouterOutlet>
     </IonReactRouter>
   </IonApp>