Add Unity Pipeline package support

Client/PackageLocal/com.unity.pipeline@0.4.0-exp.1/Editor/Authoring/AuthoringUndoScope.cs

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+using System;
+using UnityEditor;
+
+namespace Unity.Pipeline.Editor.Authoring
+{
+    /// <summary>
+    /// <para>
+    /// Groups all Undo operations registered during its lifetime into a single, collapsible Editor
+    /// Undo step, so a multi-step agent action reverts as one. Register mutations inside the scope
+    /// with Undo.RegisterCreatedObjectUndo / RegisterCompleteObjectUndo / etc.
+    /// </para>
+    ///
+    /// <code>
+    /// using (new AuthoringUndoScope("Create Enemy"))
+    /// {
+    ///     var go = new GameObject("Enemy");
+    ///     Undo.RegisterCreatedObjectUndo(go, "Create Enemy");
+    ///     // ... further registered mutations collapse into the same step
+    /// }
+    /// </code>
+    ///
+    /// <para>
+    /// NOTE: minimal seed for the shared safety policy (CAT-2509). AssetDatabase operations
+    /// (folder/asset creation, import) are NOT part of Unity's Undo system, so this scope only
+    /// affects scene/object mutations.
+    /// </para>
+    /// </summary>
+    public sealed class AuthoringUndoScope : IDisposable
+    {
+        private readonly int m_Group;
+
+        public AuthoringUndoScope(string name)
+        {
+            Undo.IncrementCurrentGroup();
+            m_Group = Undo.GetCurrentGroup();
+            if (!string.IsNullOrEmpty(name))
+                Undo.SetCurrentGroupName(name);
+        }
+
+        public void Dispose()
+        {
+            Undo.CollapseUndoOperations(m_Group);
+        }
+    }
+}