libzg2: implement name_owner_changed handling
libzg2: implement name_owner_changed handling

freedesktop-unofficial-mirror/zeitgeist__zeitgeist,freedesktop-unofficial-mirror/zeitgeist__zeitgeist,freedesktop-unofficial-mirror/zeitgeist__zeitgeist,freedesktop-unofficial-mirror/zeitgeist__zeitgeist,freedesktop-unofficial-mirror/zeitgeist__zeitgeist