add TypeHints for inspector viewing

typehints operate as an additional label for a given class in the inspector, allowing one to specify what class-entry to use as a tag
examples: Prefab displays prefab filename
TSStatic displays the used shape asset name
SFXEmitter displays the played sound asset
GameBase derivatives display the datablock used

Engine/source/T3D/prefab.h

@@ -60,6 +60,9 @@ public:
   
    static void initPersistFields();
 
+   /// returns the filename for this object
+   StringTableEntry getTypeHint() const override;
+   
    // SimObject
    virtual bool onAdd();
    virtual void onRemove();