Server/PacketIO: Updated CMSG_GROUP_UNINVITE_GUID structure and opcode.
Server/PacketIO: Updated CMSG_GROUP_DISBAND opcode.
Server/PacketIO: Updated CMSG/SMSG_GROUP_SET_LEADER structures and opcodes.
Server/PacketIO: Updated CMSG/SMSG_GROUP_SET_ROLE(S) structure and opcode.