Added a PacketBroadcaster interface

this gives a bit more control over how packets are broadcasted, which might be useful if the batch format changes (e.g. adding a length prefix) for multi version.
This really ought to be unique to a protocol context instead of a network interface, but for now this is the best we can do.

src/network/mcpe/NetworkSession.php

@@ -177,16 +177,20 @@ class NetworkSession{
 	/** @var PacketSender */
 	private $sender;
 
+	/** @var PacketBroadcaster */
+	private $broadcaster;
+
 	/**
 	 * @var \Closure[]|Set
 	 * @phpstan-var Set<\Closure() : void>
 	 */
 	private $disposeHooks;
 
-	public function __construct(Server $server, NetworkSessionManager $manager, PacketPool $packetPool, PacketSender $sender, Compressor $compressor, string $ip, int $port){
+	public function __construct(Server $server, NetworkSessionManager $manager, PacketPool $packetPool, PacketSender $sender, PacketBroadcaster $broadcaster, Compressor $compressor, string $ip, int $port){
 		$this->server = $server;
 		$this->manager = $manager;
 		$this->sender = $sender;
+		$this->broadcaster = $broadcaster;
 		$this->ip = $ip;
 		$this->port = $port;
 
@@ -449,6 +453,8 @@ class NetworkSession{
 		}
 	}
 
+	public function getBroadcaster() : PacketBroadcaster{ return $this->broadcaster; }
+
 	public function getCompressor() : Compressor{
 		return $this->compressor;
 	}