Fix deferredDirectional shadow + add line in changelog

ScriptableRenderPipeline/HDRenderPipeline/CHANGELOG.md

 ### Changed, Removals and deprecations
 - Remove Resource folder of PreIntegratedFGD and add the resource to RenderPipeline Asset
 - Default number of planar reflection change from 4 to 2
+- Rename _MainDepthTexture to _CameraDepthTexture
 
 ### Bug fixes
 - Fix ConvertPhysicalLightIntensityToLightIntensity() function used when creating light from script to match HDLightEditor behavior

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Lighting/DeferredDirectionalShadow.compute

 		float raySampleDepth = startDepth + rayDepth * sampleStep;
 
 		// Depth buffer depth for this sample
-		float sampleDepth = LOAD_TEXTURE2D(_CameraDepthTexture, sampleUV).x;
 
 		bool Hit = false;
 		float depthDiff = sampleDepth - raySampleDepth;

ScriptableRenderPipeline/HDRenderPipeline/HDRP/ShaderVariables.hlsl

 // ----------------------------------------------------------------------------
 
 TEXTURE2D(_CameraDepthTexture);
+SAMPLER(sampler_CameraDepthTexture);
 
 // Main lightmap
 TEXTURE2D(unity_Lightmap);