New add Baichuan Model (#11714)

Motivation and Context
At present, the Baichuan Large Language Model is relatively popular and
efficient in performance. Due to widespread market recognition, this
model has been added to enhance the scalability of Langchain's ability
to access the big language model, so as to facilitate application access
and usage for interested users.

System Info
langchain： 0.0.295
python：3.8.3
IDE：vs code

Description
Add the following files:

1. Add baichuan_baichuaninc_endpoint.py in the
libs/langchain/langchain/chat_models
2. Modify the __init__.py file,which is located in the
libs/langchain/langchain/chat_models/__init__.py：
a. Add "from langchain.chat_models.baichuan_baichuaninc_endpoint import
BaichuanChatEndpoint"
    b. Add "BaichuanChatEndpoint" In the file's __ All__  method

Your contribution
I am willing to help implement this feature and submit a PR, but I would
appreciate guidance from the maintainers or community to ensure the
changes are made correctly and in line with the project's standards and
practices.

docs/docs/integrations/chat/baichuan_baichuaninc_endpoint.ipynb

@@ -0,0 +1,95 @@
+{
+ "cells": [
+  {
+   "attachments": {},
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Baichuan Baihuan2\n",
+    "\n",
+    "Baichuan Intelligent announced the official open-source fine-tuning of Baihuan2-7B, Baihuan2-13B, Baihuan2-13B-Chat and their 4-bit quantified versions, all of which are free and commercially available.\n",
+    "\n",
+    "According to the introduction, both Baihuan2-7B-Base and Baihuan2-13B-Base are trained on 2.6 trillion high-quality multilingual data. While retaining the excellent generation and creation capabilities of the previous generation open source model, smooth multi round dialogue ability, and low deployment threshold, the two models have significantly improved their mathematical, code, security, logical reasoning, semantic understanding, and other abilities. Compared to the previous generation 13B model, Baihuan2-13B-Base has improved mathematical ability by 49%, code ability by 46%, security ability by 37%, logical reasoning ability by 25%, and semantic understanding ability by 15%.\n",
+    "\n",
+    "Basically, these models are classified into the following types:\n",
+    "\n",
+    "- Chat\n",
+    "- Completion\n",
+    "\n",
+    "In this notebook, we will introduce how to use langchain with [Baichuan](https://api.baichuan-ai.com) mainly in `Chat` corresponding\n",
+    " to the package `langchain/chat_models` in langchain:\n",
+    "\n",
+    "\n",
+    "## API Initialization\n",
+    "\n",
+    "To use the LLM services based on Baichuan Baihuan2, you have to initialize these parameters:\n",
+    "\n",
+    "To use a wrapper, the following parameters must be set in your environment variable:\n",
+    "\n",
+    "```base\n",
+    "Baichuan_AK=API_Key\n",
+    "Baichuan_SK=secret_Key\n",
+    "```\n",
+    "\n",
+    "Both of the above need to be applied for at https://api.baichuan-ai.com\n",
+    "\n",
+    "## Current supported models:\n",
+    "\n",
+    "- Baichuan2-7B\n",
+    "- Baichuan2-13B\n",
+    "- Baichuan2-13B-Chat"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## requesting llm api endpoint："
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "\"\"\"For basic init and call\"\"\"\n",
+    "import os\n",
+    "from langchain.chat_models import BaichuanChatEndpoint\n",
+    "\n",
+    "baichuan_ak = os.getenv('Baichuan_AK')\n",
+    "baichuan_sk = os.getenv('Baichuan_SK') \n",
+    "\n",
+    "chat_model = BaichuanChatEndpoint(baichuan_ak, baichuan_sk, \"Baichuan2-13B\")\n",
+    "res = chat_model.predict(\"Hello, please introduce yourself！\")\n",
+    "print(f\"Answer：{res.text}\")\n"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "base",
+   "language": "python",
+   "name": "python3"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 3
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython3",
+   "version": "3.11.4"
+  },
+  "vscode": {
+   "interpreter": {
+    "hash": "6fa70026b407ae751a5c9e6bd7f7d482379da8ad616f98512780b705c84ee157"
+   }
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 2
+}