Add support for the latest PMMP

ProxyPacketSender.php

@@ -26,13 +26,17 @@ public function __construct(int $socketId, ProxyNetworkInterface $handler)
         $this->handler = $handler;
     }
 
-    public function send(string $payload, bool $immediate): void
+    public function send(string $payload, bool $immediate, ?int $receiptId): void
     {
         if (!$this->closed) {
             $pk = new ForwardPacket();
             $pk->payload = $payload;
 
             $this->handler->putPacket($this->socketId, $pk);
+
+            if ($receiptId !== null) { // todo: check if QUIC supports packets with a specific ack
+                $this->handler->getSession($this->socketId)?->handleAckReceipt($receiptId);
+            }
         }
     }