Moderation Feature: Purge Messages Without Requring Ban

[Exper1mental]

AFAIK there is no way to have ClemBot purge a user's messages without banning them. Worse, once they're banned, the ban command cannot be used to purge their messages as they are no longer on the server.

I propose adding the purge functionality as an additional command and claim. My thought is there should be three ways to invoke the command:

1. !purge <user-id> [opt.-reason] or !purge <user-id> all [opt.-reason] deletes all messages sent by the user
2. !purge <user-id> <time> [opt.-reason] purges all the user's messages from a set period of time from the present. e.g. !purge @Exper1mental 1h example text
3. !purge <user-id> <start-date-and-time> <stop-date-and-time> [opt.-reason] purges all the user's messages from a set period of time. e.g. !purge @Exper1mental 01/01/2022 12:00:00 AM 01/05/2022 3:00:00 PM example text

Use example:

I already have banned the user, so now I have to manually delete their messages.

If added, I could use the separate purge command to remedy this. This also would offer an easy way to purge user messages when they've been getting out of control without having to outright ban them.

[Jay-Madden]

so this is somewhat of a discord limitation, however it should be pretty easily doable with the purge method in d.py https://discordpy.readthedocs.io/en/stable/api.html?highlight=purge#discord.TextChannel.purge however this is a fairly slow and also limited method but it would work. We would accept a PR for this for sure. its a good idea, tho it should be its own command