Add support for object reference wrappers usage in hash maps and dictionaries

(cherry picked from commit eab3631c33)

Source/Engine/Content/AssetReference.h

@@ -274,3 +274,9 @@ public:
         OnSet(asset);
     }
 };
+
+template<typename T>
+uint32 GetHash(const AssetReference<T>& key)
+{
+    return GetHash(key.GetID());
+}

Source/Engine/Content/WeakAssetReference.h

@@ -229,3 +229,9 @@ public:
         OnSet(asset);
     }
 };
+
+template<typename T>
+uint32 GetHash(const WeakAssetReference<T>& key)
+{
+    return GetHash(key.GetID());
+}

Source/Engine/Scripting/ScriptingObjectReference.h

@@ -318,3 +318,9 @@ public:
         OnSet(object);
     }
 };
+
+template<typename T>
+uint32 GetHash(const ScriptingObjectReference<T>& key)
+{
+    return GetHash(key.GetID());
+}

Source/Engine/Scripting/SoftObjectReference.h

@@ -326,3 +326,9 @@ public:
         OnSet(object);
     }
 };
+
+template<typename T>
+uint32 GetHash(const SoftObjectReference<T>& key)
+{
+    return GetHash(key.GetID());
+}