Add windows implementations

Sine Striker

2023-12-01 027122452a25191b81fef8fe35f5b54768d435f2

 src/core/corewindowagent.h

@@ -24,6 +24,7 @@
            Close,
            NumSystemButton,
        };
        Q_ENUM(SystemButton)

    public Q_SLOTS:
        void showSystemMenu(const QPoint &pos);