request: auto-fetch moderation actors

[kyranet]

Is your feature request related to a problem? Please describe.

Right now, when somebody applies an action against a user, Skyra logs them as anonymous.

Describe the solution you'd like

Auto-fetch (after a delay of 30s or 1m) and edit the following logs:

• [Un]bans: Automatically edits the moderation log with the moderator who applied the action, if none was set.
• Member Updates and Message Deletes: Automatically edit if a moderator was found.
• And other actions that are shown in Audit Logs.

The ideal solution is to build a cancellable queue that starts an auto-fetch after the first entry, but aborts when all of them have been resolved (e.g. a ban add that's claimed by a moderator with the s!reason command).

Describe alternatives you've considered

N/a.

Additional context

#179 in #suggestions
#288 in #suggestions