Raise an event when a DID exchange results in a connection being established

We need the dido library to raise an event at the moment when a DID exchange results in a connection being established. This needs to happen both for the pico receiving the invitation and the one that generated it. An application ruleset (that uses io.picolabs.did-o as a module) would react to this event and maintain a list of connections, on top of the didMap function that the did-o ruleset already provides (the app ruleset is not part of what is asked for here, but is the rationale).

Event attributes need to include

1. the role of this pico (whether "inviter" or "invitee")
2. the label from the invitation
3. the DID that this pico is going to use going forward
4. the DID that the other pico has communicated for use going forward
5. anything else that is available and might be useful