Added bilibili loader (#2673) (#2724)

I've added a bilibili loader, bilibili is a very active video site in
China and I think we need this loader.

Example:
```python
from langchain.document_loaders.bilibili import BiliBiliLoader

loader = BiliBiliLoader(
       ["https://www.bilibili.com/video/BV1xt411o7Xu/",
       "https://www.bilibili.com/video/av330407025/"]
)
docs = loader.load()
```

Co-authored-by: 了空 <568250549@qq.com>

docs/modules/indexes/document_loaders/examples/bilibili.ipynb

@@ -0,0 +1,87 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "id": "66a7777e",
+   "metadata": {},
+   "source": [
+    "# Bilibili\n",
+    "\n",
+    "This loader utilizes the `bilibili-api` to fetch the text transcript from Bilibili, one of the most beloved long-form video sites in China.\n",
+    "\n",
+    "With this BiliBiliLoader, users can easily obtain the transcript of their desired video content on the platform."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 11,
+   "id": "9ec8a3b3",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "from langchain.document_loaders.bilibili import BiliBiliLoader"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 12,
+   "id": "43128d8d",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "#!pip install bilibili-api"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 13,
+   "id": "35d6809a",
+   "metadata": {
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "outputs": [],
+   "source": [
+    "loader = BiliBiliLoader(\n",
+    "    [\"https://www.bilibili.com/video/BV1xt411o7Xu/\"]\n",
+    ")"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "outputs": [],
+   "source": [
+    "loader.load()"
+   ],
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   }
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 3 (ipykernel)",
+   "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": "3.10.9"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 5
+}