chat-window: also update chat window title when the chat updates
chat-window: also update chat window title when the chat updates

Signed-off-by: Jonny Lamb <54cd04502facfcf96b325c60af9b1611ee761860@gnome.org>

GNOME/telepathy-account-widgets,GNOME/telepathy-account-widgets,Distrotech/telepathy-account-widgets,Distrotech/telepathy-account-widgets,GNOME/telepathy-account-widgets