Mime monitoring

gnome-vfs offered a way to monitor the association between mime types and default handlers for changes, with the GnomeVFSMIMEMonitor object. GIO does not offer a replacement for this functionality at this time, since we have not found a compelling use case where GnomeVFSMIMEMonitor was used. If you think you have such a use case, please report it at https://gitlab.gnome.org/GNOME/glib/issues/new.