Add optional message_id field in user interaction payload/callback

[LatvianModder]

For example, opening context menu by right-clicking message author in channel would include message_id

But opening menu from member list or mention would not include it (current behavior)

End users often don't really know the difference between the two, so it would be helpful for example, for reporting bots to be able to know the source message that user has been reported from, if available.

[appellation]

You should make both a user and a message context menu command and simply handle them the same way.