feat: packetlistener for handling Client/Server- bound packets

[Boy0000]

Registers a packet listener with for a given plugin with a given optional key
If no key is specified, use default with an index
might not need to track listener keys but

General idea is something like this

private fun registerPluginListeners() {
    interceptClientbound { packet ->
        when (packet) {
            is ClientboundAddEntityPacket -> {
                blocky.logger.e(packet.id.toString())
                packet
            }
            else -> packet
        }
    }
}

override fun onEnable() {
    
    
    commands {
        "plugin" {
            "reload" {
                executes {
                    PacketListener.unregisterListener(this)
                    registerPluginListeners()
                }
            }
        }
    }
}



override fun onDisable() {
    PacketListener.unregisterListener(this)
}