[shader graph] Allow nodes to no generate default inputs via flag. Only really usefull on base pixel node.

UnityProject/Assets/UnityShaderEditor/Editor/Source/Nodes/BaseMaterialNode.cs

 
         public string[] m_PrecisionNames = {"half"};
 
+        protected virtual bool generateDefaultInputs { get { return true; } }
+        
         public SlotValue GetSlotDefaultValue(string slotName)
         {
             var found = m_SlotDefaultValues.FirstOrDefault(x => x.slotName == slotName);
 
         public virtual void GeneratePropertyUsages(ShaderGenerator visitor, GenerationMode generationMode, ConcreteSlotValueType slotValueType)
         {
+            if (!generateDefaultInputs)
+                return;
+
             if (!generationMode.IsPreview())
                 return;
 

UnityProject/Assets/UnityShaderEditor/Editor/Source/Nodes/PixelShaderNode.cs

             get { return 300; }
         }
 
+        protected override bool generateDefaultInputs { get { return false; } }
+
         public override void OnEnable()
         {
             base.OnEnable();