GuildMemberList, as of this commit, can generate a correct list
and handle (some of) the data given in OP 14. The implementation
is still rudimentary and there's a lot of work to finish.
- dispatcher: add LazyGuildDispatcher
- gateway.state_manager: add states_raw to fetch
a single state without uid
- gateway.websocket: remove rudimentary implementation
(moved it to GuildMemberList in litecord.pubsub.lazy_guild)