We establish the persistent congestion out of any congestion controller to improve the algorithms genericity. This path characteristic detection may be implemented regarless of the underlying congestion control algorithm. Send congestion (loss) event using directly quic_cc_event(), so without qc_cc_loss_event() wrapper function around quic_cc_event(). Take the opportunity of this patch to shorten "newest_time_sent" member field of quic_cc_event to "time_sent".