Added depth only pass to unlit

ScriptableRenderPipeline/LightweightPipeline/LWRP/Shaders/LightweightStandardUnlit.shader

             }
             ENDHLSL
         }
+
+        Pass
+        {
+            Tags{"LightMode" = "DepthOnly"}
+
+            ZWrite On
+            ColorMask 0
+
+            HLSLPROGRAM
+            // Required to compile gles 2.0 with standard srp library
+            #pragma prefer_hlslcc gles
+            #pragma exclude_renderers d3d11_9x
+            #pragma target 2.0
+
+            #pragma vertex DepthOnlyVertex
+            #pragma fragment DepthOnlyFragment
+
+            // -------------------------------------
+            // Material Keywords
+            #pragma shader_feature _ALPHATEST_ON
+
+            //--------------------------------------
+            // GPU Instancing
+            #pragma multi_compile_instancing
+
+            #include "LWRP/ShaderLibrary/LightweightPassDepthOnly.hlsl"
+            ENDHLSL
+        }
     }
     FallBack "Hidden/InternalErrorShader"
     CustomEditor "LightweightUnlitGUI"