Bulk online listing on login

when logging into a server, sending login messages one by one quickly hits discord api limits #2

they're also not really logins, since the players have been online before the time of the message

solution: send a different message on login¹ to the same webhook, containing a list of all player names in one message

¹: have an onJoin hook wait for the player list to be populated and then send it out

this could get problematic with many players when it hits the message length limit of 2000 chars, but this is not likely for civclassic in the near future so it's a good workaround

need to figure out how the message will be formatted: fixed format, global config, or derived from the filter