ConstrainedBox without setting AspectRatio throws exception

### Describe the bug


If a `ConstrainedBox` does not set the `AspectRatio`, it will throw an exception.

### Regression

_No response_

### Reproducible in sample app?

- [ ] This bug can be reproduced in the sample app.

### Steps to reproduce

```text
1. Create a `ConstrainedBox`.
2. Access its `AspectRatio` property.
3. Exception will be throw.
```

### Expected behavior

No crash.

### Screenshots

_No response_

### 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 11 21H2 (Build 22000)
- [X] Other (specify)

### Other Windows Build number

22635

### 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)
- [ ] Other (specify)

### Other SDK version

_No response_

### Visual Studio Version

2022

### Visual Studio Build Number

17.11.0

### Device form factor

Desktop

### Nuget packages

CommunityToolkit.Uwp.Controls.Primitives 8.1.240821

### Additional context

_No response_

### Help us help you

No.