Automatic message log deleting

[woodiertexas]

Is your feature request related to a problem? Please describe.
I have to manually wipe message logs every month.

Describe the solution you'd like
Automatic wiping of message logs every month to protect user privacy.

Describe alternatives you've considered
Cloning the "msg-logs" channel and then telling lily to log in the cloned channel then deleting the old "msg-logs" channel.

Additional context
Quilt Community's automatic message log deletion system

[tempest15]

Duplicate of #280