[SettingsExpander] Element in ItemsTemplate do not have DataContext

### Describe the bug

```xml

```

From the `Button_Loaded`, I can get the instance of the button. However, it's DataContext is null instead of `MyModel`

### Steps to reproduce

```text
As described above
```

### Expected behavior

+ UI element in the DataTemplate should be able to get the DataContext

### Screenshots

_No response_

### Code Platform

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

### Windows Build Number

- [ ] Windows 10 1809 (Build 17763)
- [ ] Windows 10 1903 (Build 18362)
- [ ] Windows 10 1909 (Build 18363)
- [ ] Windows 10 2004 (Build 19041)
- [ ] Windows 10 20H2 (Build 19042)
- [ ] Windows 10 21H1 (Build 19043)
- [ ] Windows 10 21H2 (Build 19044)
- [ ] Windows 10 22H2 (Build 19045)
- [ ] Windows 11 21H2 (Build 22000)
- [ ] Windows 11 22H2 (Build 22621)
- [ ] Windows 11 23H2 (Build 22631)
- [ ] Windows 11 24H2 (Build 26100)
- [x] Windows 11 25H2 (Build 26200)
- [ ] Windows 11 26H1 (Build 28000)
- [ ] 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)
- [x] Windows 10, version 2004 (Build 19041)
- [ ] Windows 10, version 2104 (Build 20348)
- [ ] Windows 11, version 22H2 (Build 22000)
- [ ] Windows 11, version 24H2 (Build 26100)
- [ ] Windows 11, version 25H2 (Build 26200)
- [ ] Windows 11, version 26H1 (Build 28000)
- [ ] Other (specify)

### Other SDK version

_No response_

### Visual Studio Version

2026

### Visual Studio Build Number

_No response_

### Device form factor

Desktop

### Additional context

_No response_

### Help us help you

No, I'm unable to contribute a solution.