Add vertex color input label to bound input type

com.unity.shadergraph/Editor/Data/Graphs/VertexColorMaterialSlot.cs

 using System;
 using UnityEditor.Graphing;
 using UnityEngine;
+using UnityEditor.ShaderGraph.Drawing.Slots;
+using UnityEngine.Experimental.UIElements;
 
 namespace UnityEditor.ShaderGraph
 {
                                        ShaderStage shaderStage = ShaderStage.Dynamic, bool hidden = false)
             : base(slotId, displayName, shaderOutputName, SlotType.Input, Vector3.zero, shaderStage, hidden)
         {}
+
+        public override VisualElement InstantiateControl()
+        {
+            return new BoundInputVectorControlView("Vertex Color");
+        }
 
         public override string GetDefaultValue(GenerationMode generationMode)
         {