Broadcast system never reuses packets, because every session has a different serializer context

[dktapps]

Description

https://github.com/pmmp/PocketMine-MP/blob/b13e97de3d3fb5ff8dd155cf61f5238426ecb15e/src/network/mcpe/StandardPacketBroadcaster.php#L44-L62

This code divides up packet recipients by their packet serializer context. The purpose of this is to allow packets to be encoded differently for different context (to potentially allow for multi version broadcasts in the future).

However, in a moment of epic dumbfuckery, I made every session have its own packet serializer context, as seen here:

https://github.com/pmmp/PocketMine-MP/blob/b13e97de3d3fb5ff8dd155cf61f5238426ecb15e/src/network/mcpe/NetworkSession.php#L215-L216

This means that the broadcaster will encode a separate copy of the packet for every single session, exactly as it was doing before 4.16.0.

[dktapps]

Fixed in next-minor by fa7c38276cc9f44765b70e488b559e3711d39965.