If we join first, it is possible that our member event is not the invite
event anymore. As such we should fetch that state first, before joining.
But also there is little reason not to mark the room as a DM
immediately. That prevents the room from temporarily becoming a group
room, that might be visible in the UI temporarily.
fixes https://gitlab.com/famedly/company/product-management/-/issues/1006
47c54cb397