Add override context factories

Sine Striker

2023-12-07 bdbe25895fefbbcf7a940d98695b56999cd1ae9e

 src/core/contexts/win32windowcontext_p.h

@@ -37,6 +37,9 @@
        bool customWindowHandler(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam,
                                 LRESULT *result);

        static bool nonClientCalcSizeHandler(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam,
                                             LRESULT *result);

    protected:
        WId windowId = 0;