Chatbot
Composable function for the top app bar on the chatbot screen.
This app bar includes:
A title "Chat With Zeke".
A menu icon that invokes openDrawer.
An action button that navigates to the chat list screen using onNavigateToChatList.
Parameters
open
Lambda function to open the navigation drawer when the menu icon is clicked.
on
Lambda function to navigate to the chat list screen when the button is clicked.