Proper QualitySettings interface

InitializeFrameSettings properly enables/disables MSAA path depending on the QualitySettings.antiAliasing value

We should probably display this in the AdditionalCameraData in the future.

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Camera/HDCamera.cs

 
             if (frameSettings.enableMSAA)
             {
-                //tempDesc.msaaSamples = HDRenderPipeline.kMsaaSamplesFixed;
+                // this is already pre-validated to be a valid sample count by InitializeFrameSettings
-                if (sampleCount < 1)
-                {
-                    Debug.LogFormat("MSAA sample count clamped");
-                    sampleCount = 1;
-                }
+            {
+                Debug.Log("No MSAA enabled");
-
+            }
             tempDesc.depthBufferBits = 0;
             tempDesc.autoGenerateMips = false;
             tempDesc.useMipMap = false;

ScriptableRenderPipeline/HDRenderPipeline/HDRP/HDRenderPipeline.cs

         int m_DebugFullScreenTempRT;
         bool m_FullScreenDebugPushed;
 
-        // temp hack
-        public const int kMsaaSamplesFixed = 4;
-
         public HDRenderPipeline(HDRenderPipelineAsset asset)
         {
             SetRenderingFeatures();

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Lighting/LightLoop/LightLoop.cs

                 {
                     kernelName += "_DepthRT";
 
-                    // if MSAA is actually active, use the MSAA path
-                    //if (m_FrameSettings.enableMSAA && 
-                    //    (HDRenderPipeline.kMsaaSamplesFixed > 1))
                     if (m_FrameSettings.enableMSAA)
                         kernelName += "_MSAA";
                 }

ScriptableRenderPipeline/HDRenderPipeline/HDRP/RenderPipeline/FrameSettings.cs

             aggregate.enableTransparentObjects = srcFrameSettings.enableTransparentObjects;
 
             aggregate.enableMSAA = srcFrameSettings.enableMSAA && renderPipelineSettings.supportMSAA;
+            if (QualitySettings.antiAliasing < 1)
+                aggregate.enableMSAA = false;
             if (aggregate.enableMSAA)
             {
                 // Initially, MSAA will only support forward