Improve typing of interaction followup send

[onerandomusername]

Summary

Interaction.followup.send should have overloads to always return a message

What is the feature request for?

The core library

The Problem

Interaction.followup.send doesn't say it always returns a message instance. Additionally, avatar_url and username are not supported for followups.

The Ideal Solution

Interaction.followup.send should be typed to always return a disnake.Message instance, and not take a wait, username, or avatar_url parameter, at least in typing overloads.

The Current Solution

No response

Additional Context

No response