Remove prefab undo cache dependency on CreatePrefab use case

Code/Framework/AzToolsFramework/AzToolsFramework/Prefab/Link/Link.cpp

@@ -234,5 +234,10 @@ namespace AzToolsFramework
             }
         }
 
+        PrefabDomValueConstReference Link::GetLinkPatches()
+        {
+            return PrefabDomUtils::FindPrefabDomValue(m_linkDom, PrefabDomUtils::PatchesName);
+        }
+
     } // namespace Prefab
 } // namespace AzToolsFramework

Code/Framework/AzToolsFramework/AzToolsFramework/Prefab/Link/Link.h

@@ -79,6 +79,8 @@ namespace AzToolsFramework
              */
             void AddLinkIdToInstanceDom(PrefabDomValue& instanceDomValue);
 
+            PrefabDomValueConstReference GetLinkPatches();
+
         private:
 
             /**