GitLab

* created Mode(ModeOpt) option for choosing between auto/client/server modes
* Auto mode internally switches the DHT between client and server modes based on the EvtLocalReachabilityChanged event emitted on the event bus (e.g. by AutoNAT)
* routing table management of peers that switch between client and server mode while we are connected to them (i.e. are in auto mode)
* removed Client(bool) option, becoming a DHT client is specified using Mode(ModeClient) instead

* feat: consume identify events to evaluate routing table addition
* fix: routing table no longer gets an update just because new messages have arrived or been sent
* fix: add already connected peers into the routing table before listening to events
Co-authored-by: Raúl Kripalani <raul.kripalani@gmail.com>
Co-authored-by: Aarsh Shah <aarshkshah1992@gmail.com>

Doesn't pass in time with race detector enabled.

We may fire notifications asynchronously. Well, we have to, really. We'd like:

1. Begin Open
2. Open Notifications
3. End Open
4. Begin Close
5. Close Notifications
6. End Close

However, this breaks if we allow open notifications to close connections (which,
IMO, we want).