Show a better error message when the build fails due to a missing simulator

Sample error failure:

```
actool exited with code 1

/Users/builder/azdo/_work/2/s/xamarin-macios/tests/dotnet/AppWithXCAssets/iOS/obj/Debug/net8.0-ios/iossimulator-x64/actool/cloned-assets/Assets.xcassetserror: The operation couldn’t be completed. Failed to locate any simulator runtime matching options: {
BuildVersionString = 21C52;
Platforms = (
"com.apple.platform.iphonesimulator"
);
VersionString = "17.2";
}
```

We should show a better error.