Prevents banned players from being drafted for antag roles

Created by: Kammerjunk

Last round, a guy was drafted and chosen for cult despite having cult disabled and being banned from Syndicate roles. Why was this even allowed in the first place? They'll just ahelp "wtf i dont have cult on" and they'll be right to do so. This should prevent antag-banned players from being drafted for antag roles. It does not prevent players with the respective role disabled from being drafted in emergencies since I don't know if that's too unrelated to include (and it would probably require some discussion about whether that's really necessary).

I have absolutely no idea what I'm doing here and I can't think of a good way to test this locally so I'd love some thorough review since if I mess this up, it'll mess all of cult up.