Fix issue with defaultAdditionalData creating unwanted light + fix stencilMask for deferred

ScriptableRenderPipeline/Core/CoreRP/ComponentSingleton.cs

         {
             get
             {
-                return s_Instance ?? (s_Instance = new GameObject("Default " + typeof(TType))
+                if (s_Instance == null)
-                    hideFlags = HideFlags.HideAndDontSave
-                }.AddComponent<TType>());
+                    GameObject go = new GameObject("Default " + typeof(TType)) { hideFlags = HideFlags.HideAndDontSave };
+                    go.SetActive(false);
+                    s_Instance = go.AddComponent<TType>();
+                }
+
+                return s_Instance;
             }
         }
     }

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Lighting/Deferred.shader

     Properties
     {
         // We need to be able to control the blend mode for deferred shader in case we do multiple pass
-        _SrcBlend("", Float) = 1
-        _DstBlend("", Float) = 1
+        [HideInInspector] _SrcBlend("", Float) = 1
+        [HideInInspector] _DstBlend("", Float) = 1
-        _StencilRef("", Int) = 0
-        _StencilCmp("", Int) = 3
+        [HideInInspector] _StencilMask("_StencilMask", Int) = 7
+        [HideInInspector] _StencilRef("", Int) = 0
+        [HideInInspector] _StencilCmp("", Int) = 3
     }
 
     SubShader
             Stencil
             {
+                ReadMask[_StencilMask]
                 Ref  [_StencilRef]
                 Comp [_StencilCmp]
                 Pass Keep

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Lighting/LightLoop/LightLoop.cs

                             CoreUtils.SetKeyword(m_deferredLightingMaterial[index], "SHADOWS_SHADOWMASK", shadowMask == 1);
                             CoreUtils.SetKeyword(m_deferredLightingMaterial[index], "DEBUG_DISPLAY", debugDisplay == 1);
 
+                            m_deferredLightingMaterial[index].SetInt(HDShaderIDs._StencilMask, (int)HDRenderPipeline.StencilBitMask.LightingMask);
                             m_deferredLightingMaterial[index].SetInt(HDShaderIDs._StencilRef, outputSplitLighting == 1 ? (int)StencilLightingUsage.SplitLighting : (int)StencilLightingUsage.RegularLighting);
                             m_deferredLightingMaterial[index].SetInt(HDShaderIDs._StencilCmp, (int)CompareFunction.Equal);
                             m_deferredLightingMaterial[index].SetInt(HDShaderIDs._SrcBlend, (int)BlendMode.One);

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Material/SubsurfaceScattering/CombineLighting.shader

         [HideInInspector] _StencilMask("_StencilMask", Int) = 7
     }
 
-    HLSLINCLUDE
-
-    int _StencilMask;
-
-    ENDHLSL
-
-
     SubShader
     {
         Pass

ScriptableRenderPipeline/HDRenderPipeline/HDRP/RenderPipelineResources/CopyStencilBuffer.shader

     #include "../Lighting/LightDefinition.cs.hlsl"
 
     int _StencilRef;
-    int _StencilMask;
     RW_TEXTURE2D(float, _HTile); // DXGI_FORMAT_R8_UINT is not supported by Unity
 
     struct Attributes