Mod-log improvements

[Greenfoot5]

Please describe what you'd like the bot to do
Include all attachment, system notifications and embeds on message deletes and edits.

Why should the bot do this?
Cause it gets missed and images that break server rules can't then be used as evidence.

Additional context
Subscriptions cog already does this, would be easily enough to implement, but it would be a good idea to spoiler all images.