refactor: Changed the namespace to import from SolidUtilities because of its structure change.

Author: SolidAlloy

Samples~/Usage Examples.meta

@@ -3,8 +3,8 @@
     using System;
     using System.Linq;
     using System.Reflection;
-    using SolidUtilities.Editor;
     using SolidUtilities.Editor.Extensions;
+    using SolidUtilities.Editor.Helpers;
     using SolidUtilities.Extensions;
     using UnityEditor;
     using UnityEngine;

Samples~/Usage Examples/Editor/TypeReferenceExampleEditor.cs

@@ -6,7 +6,7 @@ public class IncludeAdditionalAssemblies : TypeReferenceExample
     {
         [InfoBox("By default, only the types the class can reference directly are included in the drop-down " +
                  "list. In this example, CustomAssembly only has access to the TypeReferences assembly.")]
-        public NoAttributeStruct noAttribute;
+        public NoAttributeStruct NoAttribute;
 
         [InfoBox("But when we use [TypeOptions(IncludeAdditionalAssemblies = new []{ \"Assembly-CSharp\" })], " +
                  "we get access to all the classes in Assembly-CSharp even though CustomAssembly doesn't have a " +