Type promotion should handle UObject subclass custom operator functions

We should modify FindBestMatchingFunc_Internal for the case of UObject pins to search for a best matching subclass instead of just use the base UObject comparison. 

We could also exclude any function defined outside of an Engine module too, that way any custom added operators are not added to type promotion. 

1. Make a custom subclass of UObject
2. Add this static function to a BP function lib: 

3.   UFUNCTION(BlueprintPure, meta = (DisplayName = "Equal Custom Object", CompactNodeTitle = "==", Keywords = "== equal"),Category = "Test")    static bool EqualEqual_LobbyIdLobbyId(UCustomObject* A, UCustomObject* B) { return A == B; }

    

1. Open a blueprint and create a variable of type UCustomObject
2. Add the == comparison function to the graph

Result: it uses the default UObject equals comparison, not the subclasses