Discord account validation when signing up for tournaments #38
Description
A website-side alternative to fixing this issue for the Discord bot.
Prevent players from signing up to a tournament if they don't have any linked Discord accounts. If they do have a linked Discord account, automatically join them to the Tournament's server and/or provide an invite link. Only allow the registration to finish if they have joined the Discord server (i.e. check for a join event(?) or check the server's member list in intervals).