Do not ignore playlist title while saving in xspf
Seems like we are ignoring the title while saving the xspf playlist.
https://gitlab.gnome.org/GNOME/totem-pl-parser/-/blob/master/plparse/totem-pl-parser-xspf.c#L102
XSPF playlists can have a title field. Refer https://xspf.org/xspf-v1.html#rfc.section.4.1.1.2.1