Make adding autoban filters easier.

[Qwerty-133]

There's some friction in needing to run two commands when the domain is already in our filter list and also having to type [autoban] Nitro scam as the reason - which is needless since the reason will always stay the same.

I propose adding something like !bl nitroscam the_domain_name which will do all the steps mentioned above. It would also be nice if it extracts just the domain name directly when passed in a url as we don't need to be granular with scam sites by only blacklisting subdirectories.

[Qwerty-133]

On second thoughts, we'll soon not need to update existing domains but only add new ones.