成员的完整列表，这些成员属于 NIMQChatServerSubscribeAllChannelParam,包括所有继承而来的类成员

cb	NIMQChatServerSubscribeAllChannelParam
server_ids	NIMQChatServerSubscribeAllChannelParam
server_ids_count	NIMQChatServerSubscribeAllChannelParam
sub_type	NIMQChatServerSubscribeAllChannelParam
user_data	NIMQChatServerSubscribeAllChannelParam