Implement clear chat history feature in XB AI

--- AI TRACKER METADATA ---
Update Summary: Implement clear chat history feature in XB AI
Check-in Date: MM/DD/YYYY (US format) [When we should see progress/get an update]
Due Date: MM/DD/YYYY (US format) [When the issue should be fully completed]
Blocked by: [#XXXXXX] (New issues on new lines)
Additional Collaborators: @username1, @username2
AI Tracker found here: https://www.drupalstarforge.ai/
--- END METADATA ---

Overview

#3531955: AI-created new components cause loss of DeepChat message history fixed the message history problem. Now, we need a feature that allows users to clear the chat history manually.

Proposed resolution

User interface changes

Need to decide where this button/link will come in current design.