Don't mark all owned windows as dialogs.

This was preventing owner windows of non-modal dialogs from receiving key window status, meaning that input was broken in combination with embedding (Avalonia controls did work however because the routing was carried out internal to Avalonia).

native/Avalonia.Native/src/OSX/WindowImpl.mm

@@ -63,7 +63,7 @@ HRESULT WindowImpl::Show(bool activate, bool isDialog) {
     START_COM_CALL;
 
     @autoreleasepool {
-        _isDialog = isDialog || _parent != nullptr;
+        _isDialog = isDialog;
 
         WindowBaseImpl::Show(activate, isDialog);