editor: centralize engine runtime access

editor/app/Windowing/Content/EditorWindowContentController.h

@@ -51,6 +51,8 @@ class EditorHostResourceService;
 
 namespace XCEngine::UI::Editor::App {
 
+class EditorEngineServices;
+
 struct EditorWindowContentCapabilities {
     bool workspace = false;
     bool dockHost = false;
@@ -67,6 +69,7 @@ struct EditorWindowContentInitializationContext {
     Host::EditorHostResourceService& resourceService;
     UIEditorTextMeasurer& textMeasurer;
     Rendering::Host::ViewportRenderHost& viewportRenderer;
+    EditorEngineServices& engineServices;
 };
 
 struct EditorWindowContentFrameContext {