Implementation for inbound and outbound splitting

[AlexProgrammerDE]

This PR basically splits PacketProtocol into PacketProtocol and packetRegistry. A PacketProtocol defines basic stuff about the protocol like SRV and it provides incoming and outgoing Packet registries. A PacketRegistry only contains packet id mappings and everything related to the actual packet classes. The MinecraftProtocol extends the PacketProtocol and allows dynamically switching the PacketRegistries that are incoming and outgoing.