Add Actor.HasScene and Script.HasScene

Useful in managed code to check the existence of the scene in hot paths
by avoiding expensive marshalling of the Scene object.

Source/Engine/Level/Actor.h

@@ -382,6 +382,15 @@ public:
         return _isActiveInHierarchy != 0;
     }
 
+    /// <summary>
+    /// Gets value indicating if actor is in a scene.
+    /// </summary>
+    API_PROPERTY(Attributes="HideInEditor, NoSerialize")
+    FORCE_INLINE bool HasScene() const
+    {
+        return _scene != nullptr;
+    }
+
     /// <summary>
     /// Returns true if object is fully static on the scene, otherwise false.
     /// </summary>

Source/Engine/Scripting/Script.cs

@@ -17,6 +17,12 @@ namespace FlaxEngine
             }
         }
 
+        /// <summary>
+        /// Gets value indicating if the actor owning the script is in a scene.
+        /// </summary>
+        [HideInEditor, NoSerialize]
+        public bool HasScene => Actor?.HasScene ?? false; 
+
         /// <summary>
         /// Gets or sets the world space transformation of the actors owning this script.
         /// </summary>