HDRenderPipeline: Fix various warning + Add versionning to HDAdditionalData

ScriptableRenderPipeline/HDRenderPipeline/Editor/HDEditorCLI.cs

-using System;
+using System;
 using UnityEngine;
 
 namespace UnityEditor.Experimental.Rendering.HDPipeline
                             {
                                 action.operation = (CommandLineOperation)Enum.Parse(typeof(CommandLineOperation), args[i]);
                             }
-                            catch (Exception e) { }
+                            catch (Exception e) { Debug.Log(e.ToString());  }
                         }
                         break;
                     }

ScriptableRenderPipeline/HDRenderPipeline/Lighting/HDAdditionalLightData.cs

     [RequireComponent(typeof(Light))]
     public class HDAdditionalLightData : MonoBehaviour
     {
+ #pragma warning disable 414 // CS0414 The private field '...' is assigned but its value is never used
+        // We can't rely on Unity for our additional data, we need to version it ourself.
+        [SerializeField]
+        float m_Version = 1.0f;
+ #pragma warning restore 414
+            
         [Range(0.0f, 100.0f)]
         [FormerlySerializedAs("m_innerSpotPercent")]
         public float m_InnerSpotPercent = 0.0f; // To display this field in the UI this need to be public

ScriptableRenderPipeline/HDRenderPipeline/Material/Lit/Lit.hlsl

 #else
     float3 unL = lightData.positionWS - positionWS;
 
-    [branch]
     if (dot(lightData.forward, unL) >= 0.0001)
     {
         // The light is back-facing.

ScriptableRenderPipeline/HDRenderPipeline/Sky/ComputeGgxIblSampleData.compute

     float3 localL;
     float  NdotL, NdotH, LdotH;
 
-    const int validSampleCount = sampleCount;
+    const uint validSampleCount = sampleCount;
-        int acceptedSampleCount = 0;
-        int shiftedSampleIndex  = 0;
+        uint acceptedSampleCount = 0;
+        uint shiftedSampleIndex  = 0;
-        for (int i = 0; i < sampleCount; i++)
+        for (uint i = 0; i < sampleCount; i++)
         {
             // We switch to the Golden sequence instead of the Fibonacci sequence
             // since the sample count is not guaranteed to be a Fibonacci number.