implement receiving of Public Resets for the client

When a Public Reset is received, the client validates if it was sent
from the correct remote address and if the connection ID matches. When a
valid Public Reset is received, the connection is closed immediately.

server.go

@@ -20,6 +20,7 @@ type packetHandler interface {
 	Session
 	handlePacket(*receivedPacket)
 	run() error
+	closeRemote(error)
 }
 
 // A Listener of QUIC