Problem

It would be great to have ways to customize the welcome message a bit more.

Proposed Solution

Some ideas for options / settings that would be nice to have:

• ability to auto-hide the welcome message when a first message is sent (true by default)
• ability to always hide the welcome message (false by default), for those who don't want to see the message at all

Additional context

The settings part may not need to be part of jupyter-chat but could be implemented by extensions, if jupyter-chat provides a way to hide the welcome message after it was added.