x11/xdg-desktop-portal-wlr: install one chooser by default

Makes it work out-of-the-box with PipeWire-based consumers.
xdpw tries slurp -> wofi -> bemenu by default. However, a lot
of alternatives exist for wofi/bemenu e.g., fuzzel, rofi-wayland,
dmenu-wayland, nwgdmenu (from nwg-launchers).