[LYN-2255] Implemented duplication of entities with prefabs.

Code/Sandbox/Plugins/ComponentEntityEditorPlugin/SandboxIntegration.h

@@ -77,6 +77,7 @@ class CHyperGraph;
 
 namespace AzToolsFramework
 {
+    class EditorEntityAPI;
     class EditorEntityUiInterface;
 
     namespace AssetBrowser
@@ -371,6 +372,7 @@ private:
 
     AzToolsFramework::EditorEntityUiInterface* m_editorEntityUiInterface = nullptr;
     AzToolsFramework::Prefab::PrefabIntegrationInterface* m_prefabIntegrationInterface = nullptr;
+    AzToolsFramework::EditorEntityAPI* m_editorEntityAPI = nullptr;
 
     // Overrides UI styling and behavior for Layer Entities
     AzToolsFramework::LayerUiHandler m_layerUiOverrideHandler;