feat: add StreamingResponse support for ConversationalRetrievalChain chain type

[rogalvil]

Add support to Conversational Retrieval

But I not know how implement websocket example

Needs to update to version 0.0.157

Possibly it will not be necessary to create a custom response and it may work with RetrievalQAStreamingResponse

[ajndkr]

will check this out in a few hours! nice to see you actively contributing here! 😄

[ajndkr]

@rogalvil i think the solution revolves around this line: https://github.com/ajndkr/fastapi-async-langchain/blob/3266a94e8bdf2e24b2a0dc7f0b73b2322f04d099/fastapi_async_langchain/websockets/base.py#L30

instead of receive_text(), we should use receive() and detect if the message is text or json.

[audvin]

Question on this PR, is it functional for http but just holding for web socket support?

[ajndkr]

Question on this PR, is it functional for http but just holding for web socket support?

that's correct. I will take over this PR and update it to limit the update to http for now. we can add the websocket support later.

[ajndkr]

example curl request:

```bash
curl -N -X POST \
-H "Accept: text/event-stream" -H "Content-Type: application/json" \
-d '{
    "query": "Give me a code sample",
    "history": [
        [
            "What is a Text Splitter?",
            "Text Splitter is a module that is responsible for breaking up a document into smaller pieces, or chunks, that can be more easily processed."
        ],
        [
            "List all text splitter supported",
            "Langchain provides several different text splitters to help with processing text data. These include the Character Text Splitter, Hugging Face Length Function, Latex Text Splitter, Markdown Text Splitter, NLTK Text Splitter, Python Code Text Splitter, RecursiveCharacterTextSplitter, Spacy Text Splitter, tiktoken (OpenAI) Length Function, and TiktokenText Splitter."
        ]
    ]
}' \
http://localhost:8000/chat

Will add this later to repo docs.