Use more samples by default

Assets/ScriptableRenderLoop/HDRenderPipeline/Material/Lit/Lit.hlsl

 // Ref: Moving Frostbite to PBR (Appendix A)
 float3 IntegrateLambertIBLRef(  LightLoopContext lightLoopContext,
                                 EnvLightData lightData, BSDFData bsdfData,
-                                uint sampleCount = 2048)
+                                uint sampleCount = 4096)
 {
     float3   N            = bsdfData.normalWS;
     float3   tangentX     = bsdfData.tangentWS;
 
 float3 IntegrateDisneyDiffuseIBLRef(LightLoopContext lightLoopContext,
                                     float3 V, EnvLightData lightData, BSDFData bsdfData,
-                                    uint sampleCount = 2048)
+                                    uint sampleCount = 4096)
 {
     float3   N            = bsdfData.normalWS;
     float3   tangentX     = bsdfData.tangentWS;
 // Ref: Moving Frostbite to PBR (Appendix A)
 float3 IntegrateSpecularGGXIBLRef(  LightLoopContext lightLoopContext,
                                     float3 V, EnvLightData lightData, BSDFData bsdfData,
-                                    uint sampleCount = 2048)
+                                    uint sampleCount = 4096)
 {
     float3   N            = bsdfData.normalWS;
     float3   tangentX     = bsdfData.tangentWS;

Assets/ScriptableRenderLoop/HDRenderPipeline/Material/Lit/Resources/PreIntegratedFGD.shader

                 float3 V			        = float3(sqrt(1 - NdotV * NdotV), 0, NdotV);
                 float3 N			        = float3(0.0, 0.0, 1.0);
 
-                const int numSamples = 2048;
-        
-                float4 preFGD = IntegrateGGXAndDisneyFGD(V, N, PerceptualRoughnessToRoughness(perceptualRoughness), numSamples);
+                float4 preFGD = IntegrateGGXAndDisneyFGD(V, N, PerceptualRoughnessToRoughness(perceptualRoughness));
 
                 return float4(preFGD.xyz, 1.0);
             }

Assets/ScriptableRenderLoop/ShaderLibrary/ImageBasedLighting.hlsl

 // ----------------------------------------------------------------------------
 
 // Ref: Listing 18 in "Moving Frostbite to PBR" + https://knarkowicz.wordpress.com/2014/12/27/analytical-dfg-term-for-ibl/
-float4 IntegrateGGXAndDisneyFGD(float3 V, float3 N, float roughness, uint sampleCount)
+float4 IntegrateGGXAndDisneyFGD(float3 V, float3 N, float roughness, uint sampleCount = 4096)
 {
     float NdotV     = saturate(dot(N, V));
     float4 acc      = float4(0.0, 0.0, 0.0, 0.0);