Make HD Shader Graph sub-shader specify RenderPipeline so that it doesn't break LW support

com.unity.shadergraph/Editor/Data/SurfaceModel/SurfaceMaterialOptions.cs

             builder.AppendLine("Tags");
             using (builder.BlockScope())
             {
+                builder.AppendLine(@"""RenderPipeline""=""HDRenderPipeline""");
                 builder.AppendLine("\"RenderType\"=\"{0}\"", renderType);
                 builder.AppendLine("\"Queue\"=\"{0}\"", renderQueue);
             }