As a user, I must receive appropriate responses from the assistant

[kavitha-subr]

As a user, I must be able to receive an appropriate response to the questions I ask the assistant. I should also be able to view the conversation history.

Developer notes:
On clicking the Send message button, the backend API must be called with the text in the textbox, and both the user's question and the assistant response message must be displayed in the conversation history.
In case of an error from the API, a suitable error message must be displayed.