Added pre refraction toggle in layered shader

ScriptableRenderPipeline/HDRenderPipeline/Material/LayeredLit/LayeredLit.shader

         [HideInInspector] _ShowLayer1("_ShowLayer1", Float) = 0
         [HideInInspector] _ShowLayer2("_ShowLayer2", Float) = 0
         [HideInInspector] _ShowLayer3("_ShowLayer3", Float) = 0
+
+        // Transparency
+        [ToggleOff] _PreRefractionPass("PreRefractionPass", Float) = 0.0
     }
 
     HLSLINCLUDE

ScriptableRenderPipeline/HDRenderPipeline/Material/LayeredLit/LayeredLitTessellation.shader

         _TessellationShapeFactor("Tessellation shape factor", Range(0.0, 1.0)) = 0.75 // Only use with Phong
         _TessellationBackFaceCullEpsilon("Tessellation back face epsilon", Range(-1.0, 0.0)) = -0.25
         // TODO: Handle culling mode for backface culling
+
+        // Transparency
+        [ToggleOff] _PreRefractionPass("PreRefractionPass", Float) = 0.0
     }
 
     HLSLINCLUDE