Split Apple platform target and move platform state ownership

src/legacy_app_runtime_shell_services.cpp

@@ -110,10 +110,11 @@ void execute_legacy_app_ui_thread_stop(App& app)
 
 void App::draw(float dt)
 {
+    const auto vr_session = vr_session_snapshot();
     const auto draw_plan = pp::app::plan_app_frame_draw(
         canvas != nullptr,
         canvas && canvas->m_canvas,
-        vr_active,
+        vr_session.vr_active,
         ui_visible,
         vr_only);