P2P: Make GO negotiation peer and group information available over D-Bus

P2P: Make GO negotiation peer and group information available over D-Bus

The GO negotiation response is very cryptic at the moment. For a success
message we only know on which interface the negotiation succeeded, not
which peer. For a failure we know the interface also and a status code
(number).

It will be very useful for clients to know upon receipt of such a message
which peer the negotiation occurred with.

Now that the peer information is available and the API is changed
already, the function composing the D-Bus message might as well include
all GO negotiation information. This is done with a dict to make things
easier on clients if this result information changes down the line.

Signed-hostap: Reinette Chatre <reinette.chatre@intel.com>
Signed-hostap: Johannes Berg <johannes.berg@intel.com>