Suggestion: Make ShinyChat compatible with ui.toolbar

Hi, I was hoping when reading py-shiny [changelog for 1.6.0 including ui.toolbar](https://github.com/posit-dev/py-shiny/pull/2155) that showed a [demo where a rich toolbar is built with a custom chat element](https://shiny.posit.co/py/api/core/ui.toolbar.html#examples-1) that it would be compatible with shinychat. However, shinychat requires an input element thus making it redundant to both have the toolbar with rich elements and the chat UI with the input element. I suppose the simplest fix would be to add a parameter that prevents the input from rendering, a more advanced one would be to allow for a toolbar to be added to the ui.chat. Keep up the great work!