Added IExecutable and ISlotContainer interface.

Changed SlotContainerNode to ExecutableNode

Sample/Runtime/Models/Nodes/Output.cs

@@ -0,0 +1,18 @@
+using UnityEngine;
+
+namespace Misaki.GraphView.Sample
+{
+    [NodeInfo("Output Node", "Output")]
+    public class Output : BackTraceExecutableNode
+    {
+        [NodeInput]
+        private float _input;
+        
+        protected override bool OnExecute()
+        {
+            GraphObject.Logger.LogInfo(this, $"{_input}");
+
+            return true;
+        }
+    }
+}