[Purge] Feature Request: Add the ability to purge messages from a User by ID that is no longer in the server

[XxInvictus]

Hi and thankyou for the amazing cog!

I just had the request to be able to Purge a users messages by ID when they no longer exist within the server. In the use-case I am looking at we have banned the user but currently do not have an easy way to purge their messages particularly to respect their privacy in "Real Life" channels.

Of course I specified by User ID but I only specified that as it may not be practical to try and fetch a user ID for a user not in the server.

Thanks!

[japandotorg]

Can be done, yeah.