Switch moderation listeners to new audit log event

[sciwhiz12]

This PR switches our moderation event listeners from the various gateway events to the new audit log entry creation event.

Our previous system meant that we would have to manually query the audit log to retrieve the editor/moderator who performed the action, which is cumbersome and prone to timing issues (whether the gateway event is fired first or the audit log is updated first, and whether there are other audit log entries before the relevant one).

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Tasks needed to be done before merge:

• Switch to the new event in RoleEvents
  • This requires testing to discover what exactly the audit log change contains for roles being added or removed.
  • Additionally, what does the audit log entry look like with integration (Server Boosting) or linked roles?
• Yeet Utils#getAuditLog
• Reduce code duplication of embeds in ModerationEvents
  • There should at least be a method which prepopulates a builder which handles the common features (footer, timestamp, possibly the color as well).
  • Not today.
• Test the new functionality
  • Test by fire.

[Matyrobbrt]

Please use retrieveUser/MemberById with a possible ErrorHandler instead of getUser/MemberById.