feat(wayland): popup window

[wusyong]

While we can use muda to create context menu, it requires GTK as dependency. We want to go with more native approach so I'm researching smithay-client-toolkit at the moment. According to wayland protocol, we need to get window's wl_surface and obtain xdg_surface for it. This means we also needs to get the xdg_wm_base global, but smithay_client_toolkit doesn't seem to have anywhere to explain how to get this. The rests steps are almost from the method of xdg_wm_base as well.

If we could get the wl_surface of the popup window, we can think about how to add it into our Window type. Hence, it will be able to become a webview and render the menu we want to display.