[Sdk] Add UnoFeature for Uno.UI.RuntimeTests.Engine

### What would you like to be added

```xml
<UnoFeatures>
  RuntimeTests
</UnoFeatures>
```

### Why is this needed

It would be good to continue to expand on the UnoFeatures with additional functionality. This could also be done to help with unoplatform/uno#17375

### For which platform

_No response_

### Anything else we need to know?

_No response_