Allow adding a player name to the /ma join command

[Josh65-2201]

Feature request

Short description

It currently only has arena as an optional. /ma join <arena> <player> would allow command blocks to work with this and in the console if needed.

Implementation details

A permission to allow a moderator in game to run this command would be need like mobarena.join.other

[garbagemule]

I think this is a duplicate of #594, so I'm gonna close the issue for now, but please feel free to reopen it if the other issue doesn't cover this use case. From what I understand this is already doable with a sudo style plugin.