Added sending of extra CONNECTION_CLOSE frames. According to quic-transport draft 28 section 10.3.1: When sending CONNECTION_CLOSE, the goal is to ensure that the peer will process the frame. Generally, this means sending the frame in a packet with the highest level of packet protection to avoid the packet being discarded. After the handshake is confirmed (see Section 4.1.2 of [QUIC-TLS]), an endpoint MUST send any CONNECTION_CLOSE frames in a 1-RTT packet. However, prior to confirming the handshake, it is possible that more advanced packet protection keys are not available to the peer, so another CONNECTION_CLOSE frame MAY be sent in a packet that uses a lower packet protection level.