MUC history settings
The Agent::join_room method should have an argument for room history settings.
Current behavior: join_room requests history, messages are received on the client event loop without a clear indication that it's a historical message and not a present one -> generate bot spam
Desired behavior: join_room takes an Option<xmpp_parsers::muc::History>
setting. The recommended setting is None and the documentation states that this option is only for backwards-compatibility and modern clients/servers should use MAM.