Allow bots to edit/add embeds to messages

Bots could use this for better link previews (e.g. when someone sends a link to osu user which would currently just show the title and description, the bot could delete the default embed and add own embed with more data about the user) or for announcements sent by server owner.

This would be a pretty big breaking change though, so it would require a bump in discord API as many automods get triggered when a users message has an embed of type rich.