Message update event, add previous/old content to the event

[daneyOwner]

Hey there, I have had a lot of issue with having to cache the messages from all of the the channels, these issues are as follows, rate limits and the amount of space it takes up for no reason if it was just sent with the message update event.

I propose that you send the old message content(embeds) with the new as an old and new message. This will save over all a lot of computation and storage space. Thank you ;).

[erkinalp]

intentionally not sent, anyone that has accidentally sent a secret then redacted it would know why
changing it would mean a breaking change in discord's social contract