Update duels

[riccardofano]

• update the wanted_accepter to be camelCase (this is what rust does to your brain)
• check if the wantedAccepter is on cooldown before creating a duel, this decreases the likelihood of the duel staying there not accepted and having to time out because it's impossible to join
• reduce the need of having to specify { ephemeral: true, allowedMentions: { repliedUser: false } }, the helper function should be used in other commands moving forward.
• Don't allow chat to fight bots.