Added RelayNodeView;

Chnaged GraphView to multiple files for better organization;

Runtime/Models/Nodes/StickyNoteData.cs

@@ -0,0 +1,22 @@
+using System;
+using UnityEditor.Experimental.GraphView;
+using UnityEngine;
+
+namespace Misaki.GraphView
+{
+    [Serializable]
+    public class StickyNoteData
+    {
+        [SerializeField]
+        private string _id = Guid.NewGuid().ToString();
+        
+        public string title;
+        public string contents;
+        public Rect position;
+        
+        public StickyNoteTheme theme;
+        public StickyNoteFontSize fontSize;
+        
+        public string Id => _id;
+    }
+}