Menus have window type _NET_WM_WINDOW_TYPE_NORMAL instead of _NET_WM_WINDOW_TYPE_POPUP_MENU

This appears to a regression of https://bugreports.qt.io/browse/QTBUG-55558

Qt sets window type NET_WM_TYPE_NORMAL on context menus.

Steps to reproduce:
1. Open a Qt 6 based application (I used qutebrowser).
2. right click to open the context menu
3. get xprop of the menu

For the last 2 steps, what I did is to first run
sleep 2 && xdotool search --name --onlyvisible '.*' | xargs -L 1 xprop -id
And then open the context window within 2 seconds, and find the xprop output corresponding to the window by looking at the dimensions.

The bug is found by the discussion here: https://github.com/qutebrowser/qutebrowser/issues/7856