Currently, the NetworkInterfaceTL returns SocketException as a status, which is converted to a RemoteCommandResponse without HostAndPort. It is useful to know exactly which HostAndPort caused this issue.

Making this change caused some issues with ReplicaSetMonitor (probably expecting a Status instead of RemoteCommandResponse on hello or pings). Fix this and other issues that appear due to this change. 

In AsyncRPC and AsyncRequestsSender, because no HostAndPort associates with SocketException/HostUnreachable, the HostAndPort used to update the ReplicaSetMonitor is (wrongly) the first HostAndPort in RemoteCommandRequest's target vector. This target is arbitrary and could be wrong.