Prevent users from using reactions from other servers

[eibex]

The bot can only use unicode emojis or reactions uploaded to the server it is being used on. If nitro users try to use reactions from other servers the bot should refuse to use them and warn the user instead of just returning errors after the creation process.

[eibex]

A simple way to check if a reaction would return an error 400 is to make the bot react to the :reaction: @role message with the reaction used. If an error is caught, then don't write anything to CSV and warn the user.