add a convenient API

Yuhang Zhao

2023-12-19 f9aa4aacae56e3a82bce492196ff1802f3ecaf02

 src/quick/quickwindowagent_p.h

@@ -16,6 +16,10 @@

        // Host
        QQuickWindow *hostWindow{};

#ifdef Q_OS_WINDOWS
        void setupWindows10BorderWorkaround();
#endif
    };

}