Fix issue with shader resource of sky

- Move all Sky shader to RenderPipeline resources to avoid error when
creating template
- Fix naming inconsistency with sky: skyHDRI => hdriSky SkyProcedural =>
ProceduralSky

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Editor/HDAssetFactory.cs

                 newAsset.computeGgxIblSampleData = Load<ComputeShader>(HDRenderPipelinePath + "Material/GGXConvolution/ComputeGgxIblSampleData.compute");
                 newAsset.GGXConvolve = Load<Shader>(HDRenderPipelinePath + "Material/GGXConvolution/GGXConvolve.shader");
                 newAsset.opaqueAtmosphericScattering = Load<Shader>(HDRenderPipelinePath + "Sky/OpaqueAtmosphericScattering.shader");
+                newAsset.hdriSky = Load<Shader>(HDRenderPipelinePath + "Sky/HDRISky/HDRISky.shader");
+                newAsset.proceduralSky = Load<Shader>(HDRenderPipelinePath + "Sky/ProceduralSky/ProceduralSky.shader");
 
                 // Utilities / Core
                 newAsset.encodeBC6HCS = Load<ComputeShader>(CorePath + "CoreResources/EncodeBC6H.compute");

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Editor/Sky/HDRISky/HDRISkyEditor.cs

     public class HDRISkyEditor
         : SkySettingsEditor
     {
-        SerializedDataParameter m_SkyHDRI;
+        SerializedDataParameter m_hdriSky;
 
         public override void OnEnable()
         {
-            m_SkyHDRI = Unpack(o.Find(x => x.skyHDRI));
+            m_hdriSky = Unpack(o.Find(x => x.hdriSky));
-            PropertyField(m_SkyHDRI);
+            PropertyField(m_hdriSky);
 
             EditorGUILayout.Space();
 

ScriptableRenderPipeline/HDRenderPipeline/HDRP/RenderPipelineResources/HDRenderPipelineResources.asset

   GGXConvolve: {fileID: 4800000, guid: 123ed592ad5c2494b8aed301fd609e7b, type: 3}
   opaqueAtmosphericScattering: {fileID: 4800000, guid: 326059e48e5735e46a98047eff4f0295,
     type: 3}
+  hdriSky: {fileID: 4800000, guid: 9bd32a6ece529fd4f9408b8d7e00c10d, type: 3}
+  proceduralSky: {fileID: 4800000, guid: ec63f47fd265df243a7b1d40f9ef7fe7, type: 3}
   skyboxCubemap: {fileID: 103, guid: 0000000000000000f000000000000000, type: 0}
   encodeBC6HCS: {fileID: 7200000, guid: aa922d239de60304f964e24488559eeb, type: 3}
   cubeToPanoShader: {fileID: 4800000, guid: 595434cc3b6405246b6cd3086d0b6f7d, type: 3}

ScriptableRenderPipeline/HDRenderPipeline/HDRP/RenderPipelineResources/RenderPipelineResources.cs

         public ComputeShader computeGgxIblSampleData;
         public Shader GGXConvolve;
         public Shader opaqueAtmosphericScattering;
+        public Shader hdriSky;
+        public Shader proceduralSky;
 
         public Shader skyboxCubemap;
 

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Sky/HDRISky/HDRISky.cs

     public class HDRISky : SkySettings
     {
         [Tooltip("Cubemap used to render the sky.")]
-        public CubemapParameter skyHDRI = new CubemapParameter(null);
+        public CubemapParameter hdriSky = new CubemapParameter(null);
 
         public override SkyRenderer CreateRenderer()
         {
 
             unchecked
             {
-                hash = skyHDRI.value != null ? hash * 23 + skyHDRI.GetHashCode() : hash;
+                hash = hdriSky.value != null ? hash * 23 + hdriSky.GetHashCode() : hash;
             }
 
             return hash;

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Sky/HDRISky/HDRISkyRenderer.cs

+using UnityEngine.Rendering;
+
 namespace UnityEngine.Experimental.Rendering.HDPipeline
 {
     public class HDRISkyRenderer : SkyRenderer
 
         public override void Build()
         {
-            m_SkyHDRIMaterial = CoreUtils.CreateEngineMaterial("Hidden/HDRenderPipeline/Sky/SkyHDRI");
+            var hdrp = GraphicsSettings.renderPipelineAsset as HDRenderPipelineAsset;
+            m_SkyHDRIMaterial = CoreUtils.CreateEngineMaterial(hdrp.renderPipelineResources.hdriSky);
         }
 
         public override void Cleanup()
 
         public override void RenderSky(BuiltinSkyParameters builtinParams, bool renderForCubemap)
         {
-            m_SkyHDRIMaterial.SetTexture(HDShaderIDs._Cubemap, m_HdriSkyParams.skyHDRI);
+            m_SkyHDRIMaterial.SetTexture(HDShaderIDs._Cubemap, m_HdriSkyParams.hdriSky);
             m_SkyHDRIMaterial.SetVector(HDShaderIDs._SkyParam, new Vector4(m_HdriSkyParams.exposure, m_HdriSkyParams.multiplier, -m_HdriSkyParams.rotation, 0.0f)); // -rotation to match Legacy...
 
             // This matrix needs to be updated at the draw call frequency.

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Sky/HDRISky/HDRISky.shader

-Shader "Hidden/HDRenderPipeline/Sky/SkyHDRI"
+Shader "Hidden/HDRenderPipeline/Sky/HDRISky"
 {
     HLSLINCLUDE
 

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Sky/ProceduralSky/ProceduralSky.shader

 //  It's been ported to HDRP in order to have a basic procedural sky
 //  It has been left mostly untouched but has been adapted to run per-pixel instead of per vertex
 // ==================================================================================================
-Shader "Hidden/HDRenderPipeline/Sky/SkyProcedural"
+Shader "Hidden/HDRenderPipeline/Sky/ProceduralSky"
 {
     HLSLINCLUDE
 

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Sky/HDRISky/HDRISky.shader.meta

+fileFormatVersion: 2
+guid: 9bd32a6ece529fd4f9408b8d7e00c10d
+ShaderImporter:
+  externalObjects: {}
+  defaultTextures: []
+  nonModifiableTextures: []
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Sky/HDRISky/Resources.meta

-fileFormatVersion: 2
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-folderAsset: yes
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