A websocket dial may hand for an unreasonably long time and a nostr client
has no control over this when trying to connect to a relay.
Go started introducing context in networking since 2014 -
see https://go.dev/blog/context - and by now many net functions have
XxxContext equivalent, such as DialContext.
Example usage of the change introduced by this commit:
ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
defer cancel()
r, err := nostr.RelayConnectContext(ctx, "ws://relay.example.org")
The code above makes RelayConnectContext last at most 3 sec, returning
an error if a connection cannot be established in the given time.
This helps whenever a tight control over connection latency is required,
such as distributed systems.
The change is backwards-compatible except the case where RelayPool.Add
sent an error over the returned channel without actually closing said
channel. I believe it was a bug.
