Properties on a child instanced class do not appear in the UMG Bind menu

Currently, properties added to a native class in a derived blueprint class are not being recognized by the Bind menu on UserWidgets. The only way to make additional properties appear in this list is to declare them on the native base class.

1. Create a EditInlineNew class UUserWidgetTheme with a single FLinearColor property called "BaseColor"
2. Create a C++ class UThemedUserWidget with a single instanced property of type UUserWidgetTheme called "MyTheme"
3. In the editor, create a UserWidget and set the base class to your derived UThemedUserWidget class
4. Set MyTheme to your UUserWidgetTheme class
5. Observe that you can now bind properties on that UserWidget to BaseColor
6. Create a BP child of UUserWidgetTheme called DerivedTheme with an additional property DerivedColor
7. Change MyTheme to point to DerivedTheme
8. Note that you cannot select DerivedColor in the bind menu