CommunityToolkit.WinUI.UI.FrameworkElementExtensions.FindChild throw System.InvalidCastException with CollectionView

### Describe the bug

CommunityToolkit.WinUI.UI.FrameworkElementExtensions.FindChild throw System.InvalidCastException when a view contains CollectionView

### Steps to reproduce

```text
create a view with ListView
create CollectionView with CollectionView.Source = IEnumerable where T is interface;
ListView.ItemsSource bind to CollectionView.View
try to find any FrameworkElement on the view
```

### Expected behavior

FindChild must return found element or null if view doesn't contain it.

### Screenshots

_No response_

### Code Platform

- [ ] UWP
- [X] WinAppSDK / WinUI 3
- [ ] Web Assembly (WASM)
- [ ] Android
- [ ] iOS
- [ ] MacOS
- [ ] Linux / GTK

### Windows Build Number

- [X] Windows 10 1809 (Build 17763)
- [X] Windows 10 1903 (Build 18362)
- [X] Windows 10 1909 (Build 18363)
- [X] Windows 10 2004 (Build 19041)
- [X] Windows 10 20H2 (Build 19042)
- [X] Windows 10 21H1 (Build 19043)
- [X] Windows 10 21H2 (Build 19044)
- [X] Windows 10 22H2 (Build 19045)
- [X] Windows 11 21H2 (Build 22000)
- [ ] Other (specify)

### Other Windows Build number

_No response_

### App minimum and target SDK version

- [ ] Windows 10, version 1809 (Build 17763)
- [ ] Windows 10, version 1903 (Build 18362)
- [ ] Windows 10, version 1909 (Build 18363)
- [ ] Windows 10, version 2004 (Build 19041)
- [ ] Windows 10, version 2104 (Build 20348)
- [X] Windows 11, version 22H2 (Build 22000)
- [ ] Other (specify)

### Other SDK version

_No response_

### Visual Studio Version

_No response_

### Visual Studio Build Number

_No response_

### Device form factor

_No response_

### Additional context

Test example
[CollectionViewTest](https://github.com/megamechanic/WinUIBugs)

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CommunityToolkit.WinUI.UI.FrameworkElementExtensions.FindChild から始め、リンクされた CollectionViewTest の例を使って失敗を再現します。ソースがインターフェイスの項目型を持つ IEnumerable である CollectionView にバインドされた ListView を検証します。FindChild が一致する FrameworkElement を返すか、存在しない場合は null を返し、InvalidCastException をスローしなければ完了です。

索引モデルが issue の本文から書いたものです。