perf(network): Improve performance by reducing packet allocations and improving loop logic

[Caball009]

This PR makes modest performance improvements in the networking code by reducing the number of dynamic NetPacket allocations and breaking out loops as early as possible.

See commits for cleaner diffs.

TODO:

• Check whether it still makes sense to have NetPacket memory pooled.

[stephanmeesters]

I think it would be nice if we can change the signature of NetPacket from class NetPacket : public MemoryPoolObject to struct NetPacket. The memory pooling right now doesn't really get used, especially with your change? By the looks of it this would mostly need changes around NetPacket::ConstructBigCommandPacketList

[Caball009]

I think it would be nice if we can change the signature of NetPacket from class NetPacket : public MemoryPoolObject to struct NetPacket. The memory pooling right now doesn't really get used, especially with your change? By the looks of it this would mostly need changes around NetPacket::ConstructBigCommandPacketList

Perhaps I can just put the relevant logic from Connection::sendNetCommandMsg in a callback and pass that to NetPacket::ConstructBigCommandPacketList.