Remove asmref usage in SRP samples

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 samples](https://jira.unity3d.com/browse/XPIPELINE-918), part of the broader task [XPIPELINE-904](https://jira.unity3d.com/browse/XPIPELINE-904) to completely remove asmref usage from SRP code.

Asmref usage in this PR originated from the need to access HDRenderPipelineUI types, in order to display configuration UI to edit which settings an individual sample needs to be enabled.

The asmref files are now removed, and instead the `HighDefition.Editor` assembly does a single `[assembly: InternalsVisibleTo("Unity.RenderPipelines.HighDefinition.Samples.Common.Editor")]` call to allow the editor code of HDRP Sample to access HDRP Editor internal types.

In addition, asmdef files inside Core/HDRP Samples have been restrucuted and renamed to be more consistent with SRP naming conventions. The asmdef files are either "Runtime" or "Editor" assemblies, and the "Runtime" assemblies are not allowed to reference "Editor" assemblies. The new structure is displayed below:
![image](https://media.github.cds.internal.unity3d.com/user/3380/files/a59ed94f-d7de-438d-b465-38490d01059b)

Finally, I took an opportunity to replace some reflection code in the samples with a simpler callback.

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

Author: arttu-peltonen

Packages/com.unity.render-pipelines.core/Samples~/Common/Scripts/Editor/SamplesShowcaseEditor.cs

@@ -170,21 +170,18 @@ public override VisualElement CreateInspectorGUI()
                 var settingButton = new Button(
                 () =>
                 {
-                    if (string.IsNullOrEmpty(setting.editorAssemblyName) || string.IsNullOrEmpty(setting.editorClassName) || string.IsNullOrEmpty(setting.editorShowFunctionName))
+                    if (RequiredSettingBase.showSettingCallback != null)
                     {
-                        SettingsService.OpenProjectSettings(setting.projectSettingsPath);
-                        CoreEditorUtils.Highlight("Project Settings", setting.propertyPath, HighlightSearchMode.Identifier);
+                        RequiredSettingBase.showSettingCallback(setting);
                     }
                     else
                     {
-                        var editorAssembly = Assembly.Load(setting.editorAssemblyName);
-                        var editorClass = editorAssembly.GetType(setting.editorClassName);
-                        editorClass.GetMethod(setting.editorShowFunctionName).Invoke(null, new[] { setting });
+                        SettingsService.OpenProjectSettings(setting.projectSettingsPath);
+                        CoreEditorUtils.Highlight("Project Settings", setting.propertyPath, HighlightSearchMode.Identifier);
                     }
                 })
                 {
-                    text = setting.name,
-
+                    text = setting.name
                 };
 
                 string description = setting.description;

Packages/com.unity.render-pipelines.core/Samples~/Common/Scripts/Editor/Unity.RenderPipelines.Core.Samples.Editor.asmdef

@@ -0,0 +1,28 @@
+{
+    "name": "Unity.RenderPipelines.Core.Samples.Editor",
+    "rootNamespace": "",
+    "references": [
+        "Unity.RenderPipelines.Core.Runtime",
+        "Unity.RenderPipelines.Core.Editor",
+        "Unity.RenderPipelines.Core.Samples.Runtime",
+        "Unity.TextMeshPro",
+        "Unity.InputSystem"
+    ],
+    "includePlatforms": [
+        "Editor"
+    ],
+    "excludePlatforms": [],
+    "allowUnsafeCode": false,
+    "overrideReferences": true,
+    "precompiledReferences": [],
+    "autoReferenced": true,
+    "defineConstraints": [],
+    "versionDefines": [
+        {
+            "name": "com.unity.inputsystem",
+            "expression": "1.0.0",
+            "define": "INPUT_SYSTEM_INSTALLED"
+        }
+    ],
+    "noEngineReferences": false
+}

Packages/com.unity.render-pipelines.core/Samples~/CoreSamples.asmdef.meta renamed to Packages/com.unity.render-pipelines.core/Samples~/Common/Scripts/Editor/Unity.RenderPipelines.Core.Samples.Editor.asmdef.meta

@@ -1,5 +1,6 @@
 #if UNITY_EDITOR
 
+using System;
 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
@@ -12,11 +13,6 @@ public interface IRequiredSetting
         public bool state { get; }
         public string name { get; }
         public string description { get; }
-
-        // Following properties are required to store informations to call editor functions using reflection
-        public string editorAssemblyName { get; }
-        public string editorClassName { get; }
-        public string editorShowFunctionName { get; }
     }
 }
 #endif

Packages/com.unity.render-pipelines.core/Samples~/Common/Scripts/RequiredSettings/CoreRP_Runtime_Ref.asmref

@@ -1,4 +1,5 @@
 #if UNITY_EDITOR
+using System;
 using System.Collections;
 using System.Collections.Generic;
 using UnityEditor.Rendering;
@@ -45,10 +46,8 @@ private string[] m_propertyPathHierarchy
         }
 
         public virtual string projectSettingsPath { get; }
-
-        public virtual string editorAssemblyName => null;
-        public virtual string editorClassName => null;
-        public virtual string editorShowFunctionName => null;
+        
+        public static Action<RequiredSettingBase> showSettingCallback { get; set; } = null;
 
         public virtual SerializedProperty property
         {

Packages/com.unity.render-pipelines.core/Samples~/Common/Scripts/RequiredSettings/CoreRP_Runtime_Ref.asmref.meta

@@ -1,11 +1,10 @@
 {
-    "name": "CoreSamplesCommon",
+    "name": "Unity.RenderPipelines.Core.Samples.Runtime",
     "rootNamespace": "",
     "references": [
-        "GUID:6055be8ebefd69e48b49212b09b47b2f",
-        "GUID:df380645f10b7bc4b97d4f5eb6303d95",
-        "GUID:3eae0364be2026648bf74846acb8a731",
-        "GUID:75469ad4d38634e559750d17036d5f7c"
+        "Unity.TextMeshPro",
+        "Unity.RenderPipelines.Core.Runtime",
+        "Unity.InputSystem"
     ],
     "includePlatforms": [],
     "excludePlatforms": [],
@@ -22,4 +21,4 @@
         }
     ],
     "noEngineReferences": false
-}
+}

Packages/com.unity.render-pipelines.core/Samples~/Common/Scripts/RequiredSettings/IRequiredSetting.cs

@@ -1,5 +1,6 @@
 using System.Runtime.CompilerServices;
 
+[assembly: InternalsVisibleTo("Unity.RenderPipelines.HighDefinition.Samples.Common.Editor")]
 [assembly: InternalsVisibleTo("Unity.RenderPipelines.HighDefinition.Editor.Tests")]
 [assembly: InternalsVisibleTo("Unity.Industrial.Materials.AVRD.Editor")]
 [assembly: InternalsVisibleTo("Unity.TextMeshPro.Editor")]