Add a /locale command for non-community servers

[thegamecracks]

In non-community servers, the server's primary language (preferred locale) cannot be changed, meaning those servers won't be able to see and use other localizations for inboxes and ticket defaults. This may be solved by adding a /locale command to let an admin change the preferred locale independent of the server's primary language.

Some community servers may also benefit if they want to use a specific locale for the bot without having to change the primary language.

[thegamecracks]

This issue is low priority since I don't expect ticket bots to be used in non-community servers, but I'm leaving this here as a note regardless.