Draft spec [here](https://gitlab.xfce.org/kelnos/xfce-wayland-protocols/-/blob/main/xfce-foreign-toplevel-management-private-v1.xml?ref_type=heads). This exposes more state and controls for pager/taskbar apps to be able to implement. I also want to add something to that protocol that links wlr-foreign-toplevel-management and ext-workspace, so apps can know what workspace a toplevel is on.