New message component

[jakethekoenig]

A conversation should have a new message component. Let it take the function to call when submitted as a parameter. When clicked you should see what you typed appear with a loading thingy until the function returns an async string iterator at which point that should start filling in the next message with that content. Add an example function with toy data to the showcase so I can see it in action @mentatbot

[mentatbot[bot]]

I will start working on this issue