Support multiple message combination

[Caulm]

The main purpose of the modification is to support the 'Disangaged' message so that I know when to reset a conversation.

The 'Disangaged' message indicates that Bing AI has closed a conversation. After that, any question in this conversation will not be answered.

The 'Disengaged' messages and normal 'Chat' messages are different elements in the message array. Here is an example of a reply message array.

"messages": [
    {
        "text": "you are pig",
        "author": "user",
        "from": {
            "id": "844425719319166",
            "name": null
        },
        "createdAt": "2023-05-20T05:29:25.3984416+00:00",
        "timestamp": "2023-05-20T13:29:25.0043659+08:00",
        "locale": "en-us",
        "market": "en-us",
        "region": "us",
        "messageId": "44df347f-3196-48b7-a9fe-1b17e44904c0",
        "requestId": "44df347f-3196-48b7-a9fe-1b17e44904c0",
        "nlu": {
            "scoredClassification": {
                "classification": "DEEP_LEO",
                "score": null
            },
            "classificationRanking": [
                {
                    "classification": "DEEP_LEO",
                    "score": null
                }
            ],
            "qualifyingClassifications": null,
            "ood": null,
            "metaData": null,
            "entities": null
        },
        "offense": "Offensive",
        "feedback": {
            "tag": null,
            "updatedOn": null,
            "type": "None"
        },
        "contentOrigin": "cib",
        "privacy": null,
        "inputMethod": "Keyboard"
    },
    {
        "text": "I'm sorry but I prefer not to continue this conversation. I'm still learning so I appreciate your understanding and patience.🙏",
        "author": "bot",
        "createdAt": "2023-05-20T05:29:28.0144293+00:00",
        "timestamp": "2023-05-20T05:29:28.0144293+00:00",
        "messageId": "06c604c0-bf15-478d-81b1-0160f63ef223",
        "requestId": "44df347f-3196-48b7-a9fe-1b17e44904c0",
        "offense": "Unknown",
        "adaptiveCards": [
            {
                "type": "AdaptiveCard",
                "version": "1.0",
                "body": [
                    {
                        "type": "TextBlock",
                        "text": "I'm sorry but I prefer not to continue this conversation. I'm still learning so I appreciate your understanding and patience.🙏\n",
                        "wrap": true
                    }
                ]
            }
        ],
        "sourceAttributions": [],
        "feedback": {
            "tag": null,
            "updatedOn": null,
            "type": "None"
        },
        "contentOrigin": "DeepLeo",
        "privacy": null
        "spokenText": "I'm still learning so I appreciate your understanding and patience."
    },
    {
        "hiddenText": "> Conversation disengaged",
        "author": "bot",
        "createdAt": "2023-05-20T05:29:29.5078243+00:00",
        "timestamp": "2023-05-20T05:29:29.5078243+00:00",
        "messageId": "6f4907ea-61e4-4183-be76-9459a8f6e423",
        "requestId": "44df347f-3196-48b7-a9fe-1b17e44904c0",
        "messageType": "Disengaged",
        "offense": "None",
        "adaptiveCards": [
            {
                "type": "AdaptiveCard",
                "version": "1.0",
                "body": [
                    {
                        "type": "RichTextBlock",
                        "inlines": [
                            {
                                "type": "TextRun",
                                "isSubtle": true,
                                "italic": true,
                                "text": "> Conversation disengaged"
                            }
                        ]
                    }
                ]
            }
        ],
        "feedback": {
            "tag": null,
            "updatedOn": null,
            "type": "None"
        },
        "contentOrigin": "DeepLeo",
        "privacy": null
    }
],

In BingChatConversation.GetAnswer method, only the last 'Chat' message will be parsed, resulting in the loss of other messages.

So my plan is to combine multiple message contents in order.
Since there is no display text in the 'Disangaged' message, I used the 'MessageType' tag instead. The caller may replace it with readable text.
Other messages such as 'InternalSearchQuery' and 'InternalLoaderMessage' will also be output. I think watching AI searching internet is also a kind of fun. This combination may also be helpful for outputting 'GenerateContentQuery' messages in the future, such as image generation, as it is also multiple messages.

I also made some adjustments to the parsing of 'Chat' messages. Currently, the main content from 'Text' and the referenced content from 'sourceAttributes' will be combined, with the latter becoming footnotes.

[bsdayo]

Thanks :D