Add deferred async scene asset loading

editor/src/Application.h

@@ -6,6 +6,7 @@
 #include "Viewport/ViewportHostService.h"
 
 #include <XCEngine/Rendering/RenderContext.h>
+#include <chrono>
 #include <memory>
 #include <string>
 #include <windows.h>
@@ -65,7 +66,10 @@ private:
     ViewportHostService m_viewportHostService;
     uint64_t m_exitRequestedHandlerId = 0;
     std::wstring m_lastWindowTitle;
+    std::chrono::steady_clock::time_point m_lastFrameTime{};
+    bool m_hasLastFrameTime = false;
     bool m_renderReady = false;
+    bool m_resourceManagerInitialized = false;
 };
 
 }