[Feature request] Allow Warden filters to fetch from [p]def msg for on-message-edit actions

[sleepadru]

Cog

• Defender
• Index
• Sbansync

Basically, I'd like to be able to log the before/after message changes.
Using [p]def msg user <username>, one can obtain the recent changes to someone's message history. Creating a context variable would be helpful for message logging purposes. Many of the available cogs that exist only log to one specific channel, which limits the capability of moderators to sort through logs.