appmenu: Inherit from GtkPopover instead of GtkPopoverMenu
In Gtk4, GtkPopoverMenu is meant to be used with a menu model.
The spacing and margins are updated accordingly to get the same layout as GtkPopoverMenu.
In Gtk4, GtkPopoverMenu is meant to be used with a menu model.
The spacing and margins are updated accordingly to get the same layout as GtkPopoverMenu.