Added unlit pass rendering for opaque objects.

ScriptableRenderPipeline/LightweightPipeline/LightweightPipeline.cs

         private void RenderOpaques(ref ScriptableRenderContext context, RendererConfiguration settings)
         {
             var opaqueDrawSettings = new DrawRendererSettings(m_CurrCamera, m_LitPassName);
+            opaqueDrawSettings.SetShaderPassName(1, m_UnlitPassName);
             opaqueDrawSettings.sorting.flags = SortFlags.CommonOpaque;
             opaqueDrawSettings.rendererConfiguration = settings;