community: Add deprecation warning for GigaChat integration in langchain-community (#28022)

- **Description:** We have released the
[langchain-gigachat](https://github.com/ai-forever/langchain-gigachat?tab=readme-ov-file)
with new GigaChat integration that support's function/tool calling. This
PR deprecated legacy GigaChat class in community package.

---------

Co-authored-by: Erick Friis <erick@langchain.dev>

docs/docs/integrations/chat/gigachat.ipynb

@@ -8,7 +8,7 @@
    "source": [
     "# GigaChat\n",
     "This notebook shows how to use LangChain with [GigaChat](https://developers.sber.ru/portal/products/gigachat).\n",
-    "To use you need to install ```gigachat``` python package."
+    "To use you need to install ```langchain_gigachat``` python package."
    ]
   },
   {
@@ -22,7 +22,7 @@
    },
    "outputs": [],
    "source": [
-    "%pip install --upgrade --quiet  gigachat"
+    "%pip install --upgrade --quiet  langchain-gigachat"
    ]
   },
   {
@@ -53,20 +53,20 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 3,
+   "execution_count": 5,
    "metadata": {
     "collapsed": false
    },
    "outputs": [],
    "source": [
-    "from langchain_community.chat_models import GigaChat\n",
+    "from langchain_gigachat import GigaChat\n",
     "\n",
     "chat = GigaChat(verify_ssl_certs=False, scope=\"GIGACHAT_API_PERS\")"
    ]
   },
   {
    "cell_type": "code",
-   "execution_count": 8,
+   "execution_count": 6,
    "metadata": {
     "collapsed": false
    },

docs/docs/integrations/providers/salute_devices.mdx

@@ -9,7 +9,7 @@ For more info how to get access to GigaChat [follow here](https://developers.sbe
 GigaChat package can be installed via pip from PyPI:
 
 ```bash
-pip install gigachat
+pip install langchain-gigachat
 ```
 
 ## LLMs
@@ -25,7 +25,7 @@ from langchain_community.llms import GigaChat
 See a [usage example](/docs/integrations/chat/gigachat).
 
 ```python
-from langchain_community.chat_models import GigaChat
+from langchain_gigachat.chat_models import GigaChat
 ```
 
 ## Embeddings
@@ -33,5 +33,5 @@ from langchain_community.chat_models import GigaChat
 See a [usage example](/docs/integrations/text_embedding/gigachat).
 
 ```python
-from langchain_community.embeddings import GigaChatEmbeddings
+from langchain_gigachat.embeddings import GigaChatEmbeddings
 ```

docs/docs/integrations/text_embedding/gigachat.ipynb

@@ -15,11 +15,14 @@
    "cell_type": "code",
    "execution_count": null,
    "metadata": {
-    "collapsed": false
+    "collapsed": false,
+    "pycharm": {
+     "is_executing": true
+    }
    },
    "outputs": [],
    "source": [
-    "%pip install --upgrade --quiet  gigachat"
+    "%pip install --upgrade --quiet  langchain-gigachat"
    ]
   },
   {
@@ -50,13 +53,13 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 5,
+   "execution_count": 3,
    "metadata": {
     "collapsed": false
    },
    "outputs": [],
    "source": [
-    "from langchain_community.embeddings import GigaChatEmbeddings\n",
+    "from langchain_gigachat import GigaChatEmbeddings\n",
     "\n",
     "embeddings = GigaChatEmbeddings(verify_ssl_certs=False, scope=\"GIGACHAT_API_PERS\")"
    ]
@@ -81,13 +84,7 @@
    "outputs": [
     {
      "data": {
-      "text/plain": [
-       "[0.8398333191871643,\n",
-       " -0.14180311560630798,\n",
-       " -0.6161925792694092,\n",
-       " -0.17103666067123413,\n",
-       " 1.2884578704833984]"
-      ]
+      "text/plain": "[0.8398333191871643,\n -0.14180311560630798,\n -0.6161925792694092,\n -0.17103666067123413,\n 1.2884578704833984]"
      },
      "execution_count": 8,
      "metadata": {},