[Feature Request] Bot annotations on messages

I think it would be nice if bots had a method to 'annotate' other user's messages with rich text information.

Currently, message supplementation features require the bot to disruptively interact with the message in some other way, such as by reacting, replying, or just sending a new message.

My proposal would work something like this (mocked up by photoshopping together other modals):

A bot can send an 'annotation' to a message. The API request would include an index range from the content of the message (such as `"from": 10, "to": 30`), a title for the annotation, and then a rich text description, similar to how embeds work.

The bot would need either a new permission or a new OAuth scope in order to be able to do this.

This would help bots add additional context to messages that is useful for both convenience and bookkeeping purposes, but without the risk that comes with allowing messages to be edited directly.

Some examples of potential usage:

- A bot in a game community that detects names of weapons or moves and annotates them with their stats

- A bot in a finance or investment community that detects stock market abbreviations and annotates them with the current performance of that stock

- A bot in a language learning community that detects vocabulary and annotates them with translated dictionary entries

- A bot that detects non-permanent links (such as to the 'latest' page on a blog), and annotates them with a permalink to the post