Added MSAA support to the test framework.

Tests/GraphicsTests/Framework/Editor/TestFramework.cs

 				             (testSetup.hdr && testCamera.allowHDR) ? RenderTextureFormat.ARGBHalf : RenderTextureFormat.ARGB32,
 				             24);
 			rtDesc.sRGB = PlayerSettings.colorSpace == ColorSpace.Linear;
+            rtDesc.msaaSamples = testSetup.msaaSamples;
 
 			// render the scene
 			var tempTarget = RenderTexture.GetTemporary (rtDesc);

Tests/GraphicsTests/Framework/SetupSceneForRenderPipelineTest.cs

 
 namespace UnityEngine.Experimental.Rendering
 {
-	public class SetupSceneForRenderPipelineTest : MonoBehaviour 
+	public class SetupSceneForRenderPipelineTest : MonoBehaviour
+	    public int msaaSamples = 1;
 
 		public int width = 1280;
 		public int height = 720;

Tests/GraphicsTests/RenderPipeline/LightweightPipeline/Scenes/010_MultiplePointLights.unity

   m_TargetEye: 3
   m_HDR: 1
   m_AllowMSAA: 1
+  m_AllowDynamicResolution: 0
   m_ForceIntoRT: 0
   m_OcclusionCulling: 1
   m_StereoConvergence: 10
   renderPipeline: {fileID: 11400000, guid: e6987eea1dd29074597d54ed91a54a26, type: 2}
   cameraToUse: {fileID: 232121474}
   hdr: 0
+  msaaSamples: 4
   width: 1280
   height: 720
 --- !u!1 &235386914

Tests/GraphicsTests/RenderPipeline/LightweightPipeline/Scenes/024_Shader_PBRvalidation_Specular.unity

   renderPipeline: {fileID: 11400000, guid: e6987eea1dd29074597d54ed91a54a26, type: 2}
   cameraToUse: {fileID: 1169043407}
   hdr: 0
+  msaaSamples: 4
   width: 1280
   height: 720
 --- !u!20 &1169043407

Tests/GraphicsTests/RenderPipeline/LightweightPipeline/Scenes/025_Shader_PBRvalidation_Metallic.unity

   renderPipeline: {fileID: 11400000, guid: e6987eea1dd29074597d54ed91a54a26, type: 2}
   cameraToUse: {fileID: 1169043407}
   hdr: 0
+  msaaSamples: 4
   width: 1280
   height: 720
 --- !u!20 &1169043407