Show purgebanned in the feedback message of pban

[Akarys42]

Current when a user is banned or purgebanned this feedback message will be sent:

📨 👌 applied ban to USER permanently.

It would be nice to have purgeban instead of ban in the message.

To achieve that, we can add a purge: True entry to the infraction dictionary in

bot/bot/exts/moderation/infraction/infractions.py

Line 327 in bafa6a9

await self.apply_infraction(ctx, infraction, user, action)

And append purge at the beginning of infr_type if infraction.get('purge') is True

bot/bot/exts/moderation/infraction/_scheduler.py

Line 237 in bafa6a9

log.info(f"Applied {infr_type} infraction #{id_} to {user}.")

[Xithrius]

I'll be yoinking this one.