After switching `UserLookupCache` to `GET /users/lookup` from `GET
/users`, multiplayer sort of breaks, since the former endpoint does not
return `ruleset_statistics`, which are used in multiplayer to show
users' ranks. Therefore, switch multiplayer to use the appropriate
request type directly.
When the server requests a disconnect due to a user connecting
via a second device, the client will now log the user out on the first
device and show a notification informing them of the cause of
disconnection.
Intended to be a temporary fix for
https://github.com/ppy/osu/issues/17713 while a more permanent solution
is established. A proper fix is actually quite simple, but updating the
test to work with it is... *slightly* more complicated.
This hotfix will mean that if a `UserJoined` event arrives during the
unobserved window during room join (of the local user), the local user
still won't see the joining user, but the game won't crash as a result.