chat-manager: stop telling the chat mgr about handled rooms
chat-manager: stop telling the chat mgr about handled rooms

Now that the chat handler has moved to its own process this is no longer
enough. The instance of the chat manager in empathy doesn't know about the
handlded channels.

The chat manager should implement an Observer instead to know about all the
rooms.

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