Remove asmref usage from SRP tests

Currently in Unity 6, asmref files are sometimes used to bypass assembly visibility rules. In the future, asmref is no longer allowed so the current usage must be removed (see [RFC](https://docs.google.com/document/d/1SWAG19Ns5gnmbVl4WD-HT0f4DO2UVdiRj_YhX1o7J7E/edit#heading=h.9tfgs0fpr1tb)).

This PR solves the sub-task [Remove asmref usage in SRP tests](https://jira.unity3d.com/browse/XPIPELINE-919), part of the broader task [XPIPELINE-904](https://jira.unity3d.com/browse/XPIPELINE-904) to completely remove asmref usage from SRP code.

SRP tests used asmrefs in 3 places:

1) **HDRP_RuntimeTests project** where the test `012-SVL_Check` contains script `SVLChecker.cs` which needs access to `GenerateShaderVariantList` inside the `com.unity.testframework.graphics` package. However since that type is public, there is no need to inject this script into that assembly. We simply add an asmdef file which contains a reference to the `UnityEngine.TestTools.Graphics` assembly.

2) **VisualEffectGraph_HDRP project** contains an editor-only `TemplateEditor.cs` script which used asmref to inject itself into `Unity.VisualEffectGraph.Editor` assembly. This is unnecessary that assembly is already accessible, we can just wrap the code in `#if UNITY_EDITOR` instead.

3) **UniversalGraphicsTest_2D project** contains an editor-only `AdditionalMenuItems.cs` script which used asmref to inject itself into `UnityEditor.TestTools.Graphics` assembly from `com.unity.testframework.graphics` package. This was also unnecessary, just wrapping the code in `#if UNITY_EDITOR` is enough.


This PR is a follow-up to earlier PRs https://github.cds.internal.unity3d.com/unity/unity/pull/47596 and https://github.cds.internal.unity3d.com/unity/unity/pull/47609.

Author: arttu-peltonen

Tests/SRPTests/Projects/HDRP_RuntimeTests/Assets/HDRPDefaultResources/HDRenderPipelineGlobalSettings.asset

@@ -147,12 +147,12 @@ MonoBehaviour:
     m_AfterPostProcessCustomPostProcesses:
       m_InjectionPoint: 2
       m_CustomPostProcessTypesAsString:
-      - TvMonochrome, Assembly-CSharp, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null
+      - TvMonochrome, HDRP_RuntimeTests, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null
   beforeTransparentCustomPostProcesses: []
   beforePostProcessCustomPostProcesses: []
   afterPostProcessBlursCustomPostProcesses: []
   afterPostProcessCustomPostProcesses:
-  - TvMonochrome, Assembly-CSharp, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null
+  - TvMonochrome, HDRP_RuntimeTests, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null
   beforeTAACustomPostProcesses: []
   defaultRenderingLayerMask: 257
   renderingLayerNames:

Tests/SRPTests/Projects/HDRP_RuntimeTests/Assets/Scenes/012-SVL_Check.unity

@@ -383,7 +383,7 @@ MonoBehaviour:
     m_PersistentCalls:
       m_Calls:
       - m_Target: {fileID: 2144884655}
-        m_TargetAssemblyTypeName: SVLChecker, UnityEngine.TestTools.Graphics
+        m_TargetAssemblyTypeName: SVLChecker, HDRP_RuntimeTests
         m_MethodName: Check
         m_Mode: 1
         m_Arguments:

Tests/SRPTests/Projects/HDRP_RuntimeTests/Assets/Scenes/012-SVL_Check/SVL Checker.asmref

@@ -1,11 +1,8 @@
-using System.Collections;
-using System.Collections.Generic;
-using UnityEngine;
-using UnityEditor;
+#if UNITY_EDITOR
 using System.IO;
+using UnityEditor;
+using UnityEngine;
 using UnityEngine.TestTools.Graphics;
-using UnityEditor.TestTools.Graphics;
-
 
 public class AdditionalMenuItems : MonoBehaviour
 {
@@ -86,3 +83,4 @@ static void SelectImageDirectory()
         }
     }
 }
+#endif