Install flatpak-xdg-email and flatpak-xdg-open as xdg-email and xdg-open
    
    This matches with the flatpak-xdg-utils change that added flatpak
    prefix to flatpak-xdg-utils versions of xdg-email and xdg-open.
    
    With this change, we now include _both_ xdg-utils and flatpak-xdg-utils
    in the module build, and overwrite the xdg-utils versions of xdg-email
    and xdg-open with the flatpak-xdg-utils versions when building the
    container.