Create demo example app using textual-tty to embed a cmd2 app within a Textual app #1771

The new-ish textual-tty provides a terminal emulator for Textual apps, using bittty.

This should allow embedding a cmd2 application within a Textual application. This could enable a much richer realtime visual display of status and situational awareness information than is available with a simple bottom toolbar.

Someone should create a demo / example application showing how to do this either inside the cmd2 repo or externally where we can link to it.