Anhytran/update disconnect participant

[bigO68]

Amazon Connect Chat: Enhanced End Chat Flow Implementation

Problem Statement
The original "End Chat" button immediately terminated the WebSocket connection after calling disconnectParticipant(), preventing customers from receiving post-disconnect messages like surveys or farewell notifications.

Solution Overview
Maintain the WebSocket connection after disconnectParticipant() API call, allowing the chat to remain active until the server sends a chatEnded event.

Key Technical Changes

1. Deferred Connection Termination
   Removed immediate cleanup from disconnectParticipant() method
   Moved connection termination logic to _handleIncomingMessage() when CONTENT_TYPE.chatEnded is received

2. State Management Refactoring
   // Before: Immediate cleanup in disconnectParticipant()
   this._participantDisconnected = true;
   this.hasChatEnded = true;
   this.cleanUpOnParticipantDisconnect();
   this.breakConnection();

// After: Server-driven cleanup in _handleIncomingMessage()
if (incomingData.ContentType === CONTENT_TYPE.chatEnded) {
this.hasChatEnded = true;
this._forwardChatEvent(CHAT_EVENTS.CHAT_ENDED, {
data: null,
chatDetails: this.getChatDetails()
}, () => {
this._participantDisconnected = true;
this.cleanUpOnParticipantDisconnect();
});
this.breakConnection();
}

3. Event Ordering Fix
   Used callback pattern in _forwardChatEvent() to ensure CHAT_ENDED event is published before cleanup
   Prevents race conditions between UI notifications and connection termination