[BUG] Samples app - AppTheme isn't showing correctly when Windows system is Dark Mode

### Is there an existing issue for this?

- [X] I have searched the existing issues

### Did you read the "Reporting a bug" section on Contributing file?

- [X] I have read the "Reporting a bug" section on Contributing file: https://github.com/CommunityToolkit/Maui/blob/main/CONTRIBUTING.md#reporting-a-bug

### Current Behavior

1. Set your Windows system theme to 'Dark Mode'.
2. Launch the Samples app
3. Navigate to Essentials
4. Select AppTheme

5. Toggle the switch to 'On'

As you can see, the text for the page and the flyout is of a color that you can't see!

NOTE: It works as expected on Android!

### Expected Behavior

When the users system default is 'Dark Mode', toggling the AppTheme to 'on', the user should be able to read the text.

### Steps To Reproduce

1. Set your system theme to 'Dark Mode'.
2. THEN launch the Samples app
3. Navigate to Essentials
4. Select AppTheme
5. Toggle the switch to 'on'.

### Link to public reproduction project repository

https://github.com/CommunityToolkit/Maui

### Environment

```markdown
- .NET MAUI CommunityToolkit: 9.0.3
- OS: Windows 11 Enterprise, Version: 21H2, Build 22000.3147
- .NET MAUI: 8.0.203
```

### Anything else?

Works correctly on Android API 33. Not know if this is a bug on iOS, MacCatalyst or Tizen, as I do not have any suitable devices.