Fix dielectric specular control

It was resetting control values

com.unity.shadergraph/Editor/Drawing/Controls/DielectricSpecularControl.cs

             m_RangePanel = new VisualElement { name = "sliderPanel" };
             m_RangePanel.Add(new Label("Range"));
             Action<float> changedRangeSlider = (s) => { OnChangeRangeSlider(s); };
-            m_RangeSlider = new Slider(0.01f, 1, changedRangeSlider);
-            m_RangeSlider.value = 0.5f;
+            m_RangeSlider = new Slider(0.01f, 1, changedRangeSlider) { value = m_DielectricMaterial.range };
-            m_RangePanel.SetEnabled(true);
+            m_RangePanel.SetEnabled(m_DielectricMaterial.type == DielectricMaterialType.Common);
-            m_IORSlider = new Slider(1, 5, changedIORSlider);
-            m_IORSlider.value = 1;
+            m_IORSlider = new Slider(1, 5, changedIORSlider) { value = m_DielectricMaterial.indexOfRefraction };
-            m_IORPanel.SetEnabled(false);
+            m_IORPanel.SetEnabled(m_DielectricMaterial.type == DielectricMaterialType.Custom);
             Add(m_IORPanel);
         }
 
             value = Mathf.Max(Mathf.Min(value, 1), 0.01f);
             m_RangePanel.Remove(m_RangeSlider);
             Action<float> changedSlider = (s) => { OnChangeRangeSlider(s); };
-            m_RangeSlider = new Slider(0.01f, 1, changedSlider);
-            m_RangeSlider.value = value;
+            m_RangeSlider = new Slider(0.01f, 1, changedSlider) { value = value };
             m_RangePanel.Add(m_RangeSlider);
             m_RangePanel.Remove(m_RangeField);
             m_RangeField.value = value;
             value = Mathf.Max(Mathf.Min(value, 5), 1);
             m_IORPanel.Remove(m_IORSlider);
             Action<float> changedSlider = (s) => { OnChangeIORSlider(s); };
-            m_IORSlider = new Slider(1, 5, changedSlider);
-            m_IORSlider.value = value;
+            m_IORSlider = new Slider(1, 5, changedSlider)  { value = value };
             m_IORPanel.Add(m_IORSlider);
             m_IORPanel.Remove(m_IORField);
             m_IORField.value = value;