Make the Van der Corput sequence explicitly one-based

Assets/ScriptableRenderLoop/HDRenderPipeline/SceneSettings/SubsurfaceScatteringParameters.cs

         // Ref: http://holger.dammertz.org/stuff/notes_HammersleyOnHemisphere.html
         static float VanDerCorputBase2(uint i)
         {
+            i = i + 1;
             i = (i << 16) | (i >> 16);
             i = ((i & 0x00ff00ff) << 8) | ((i & 0xff00ff00) >> 8);
             i = ((i & 0x0f0f0f0f) << 4) | ((i & 0xf0f0f0f0) >> 4);
             // Importance sample the linear combination of two Gaussians.
             for (uint i = 0; i < numSamples; i++)
             {
-                float u   = VanDerCorputBase2(i + 1);
+                float u   = VanDerCorputBase2(i);
                 float pos = GaussianCombinationCdfInverse(u, maxStdDev1, maxStdDev2, m_LerpWeight);
                 float pdf = GaussianCombination(pos, maxStdDev1, maxStdDev2, m_LerpWeight);
 

Assets/ScriptableRenderLoop/ShaderLibrary/Hammersley.hlsl

 
 float VanDerCorputBase2(uint i)
 {
-    return float(ReverseBits32(i)) * 2.3283064365386963e-10; // 0x100000000
+    return float(ReverseBits32(i + 1)) * 2.3283064365386963e-10; // 0x100000000
 }
 
 float2 Hammersley2dSeq(uint i, uint sequenceLength)