Instead of having a NM_SUPPLICANT_INTERFACE_CONNECTION_ERROR signal to notify
about failures during AddNetwork/SelectNetwork, accept a callback to report
success/failure.
Thereby, rename nm_supplicant_interface_set_config() to
nm_supplicant_interface_assoc().
The async callback is guaranteed to:
- be invoked exactly once, signalling success or failure
- always being invoked asyncronously.
The pending request can be (synchronously) cancelled via
nm_supplicant_interface_disconnect() or by disposing the
interface instance. In those cases the callback will be invoked
too, with error code cancelled/disposing.
Also change the signature of the NM_SUPPLICANT_INTERFACE_STATE signal,
to have three "int" type arguments. Thereby also fix the subscribers
to this signal that wrongly had type guint32, instead of guint
(which happens to be the same underlying type, so no real problem).
https://mail.gnome.org/archives/networkmanager-list/2017-February/msg00021.html
As the fast-supported flag changes, update the existing supplicant
interfaces with the new information.
Also, by default assume it is supported.
(cherry picked from commit 872b9ec5ea)
