Added IExecutable and ISlotContainer interface.

Changed SlotContainerNode to ExecutableNode

Editor/Views/Blackboard/BlackboardPropertyView.cs

@@ -0,0 +1,43 @@
+using System;
+using UnityEditor.Experimental.GraphView;
+using UnityEngine.UIElements;
+
+namespace Misaki.GraphView.Editor
+{
+    public class BlackboardPropertyView : BlackboardField, IInspectable
+    {
+        private readonly ExposedPropertyEditor _editor;
+
+        public Action<IInspectable> OnItemSelected { get; set; }
+        public string InspectorName => text;
+        
+        public BlackboardPropertyView(ExposedPropertyEditor editor)
+        {
+            _editor = editor;
+        }
+
+        public override bool IsDroppable() => true;
+        
+        public override void OnSelected()
+        {
+            base.OnSelected();
+            OnItemSelected?.Invoke(this);
+        }
+        
+        public override void OnUnselected()
+        {
+            base.OnUnselected();
+            OnItemSelected?.Invoke(null);
+        }
+        
+        public virtual ExecutableNodeView CreateNodeView()
+        {
+            return null;
+        }
+
+        public virtual VisualElement CreateInspector()
+        {
+            return _editor.CreateInspector();
+        }
+    }
+}