community[major], core[patch], langchain[patch], experimental[patch]: Create langchain-community (#14463)

Moved the following modules to new package langchain-community in a backwards compatible fashion:

```
mv langchain/langchain/adapters community/langchain_community
mv langchain/langchain/callbacks community/langchain_community/callbacks
mv langchain/langchain/chat_loaders community/langchain_community
mv langchain/langchain/chat_models community/langchain_community
mv langchain/langchain/document_loaders community/langchain_community
mv langchain/langchain/docstore community/langchain_community
mv langchain/langchain/document_transformers community/langchain_community
mv langchain/langchain/embeddings community/langchain_community
mv langchain/langchain/graphs community/langchain_community
mv langchain/langchain/llms community/langchain_community
mv langchain/langchain/memory/chat_message_histories community/langchain_community
mv langchain/langchain/retrievers community/langchain_community
mv langchain/langchain/storage community/langchain_community
mv langchain/langchain/tools community/langchain_community
mv langchain/langchain/utilities community/langchain_community
mv langchain/langchain/vectorstores community/langchain_community
mv langchain/langchain/agents/agent_toolkits community/langchain_community
mv langchain/langchain/cache.py community/langchain_community
mv langchain/langchain/adapters community/langchain_community
mv langchain/langchain/callbacks community/langchain_community/callbacks
mv langchain/langchain/chat_loaders community/langchain_community
mv langchain/langchain/chat_models community/langchain_community
mv langchain/langchain/document_loaders community/langchain_community
mv langchain/langchain/docstore community/langchain_community
mv langchain/langchain/document_transformers community/langchain_community
mv langchain/langchain/embeddings community/langchain_community
mv langchain/langchain/graphs community/langchain_community
mv langchain/langchain/llms community/langchain_community
mv langchain/langchain/memory/chat_message_histories community/langchain_community
mv langchain/langchain/retrievers community/langchain_community
mv langchain/langchain/storage community/langchain_community
mv langchain/langchain/tools community/langchain_community
mv langchain/langchain/utilities community/langchain_community
mv langchain/langchain/vectorstores community/langchain_community
mv langchain/langchain/agents/agent_toolkits community/langchain_community
mv langchain/langchain/cache.py community/langchain_community
```

Moved the following to core
```
mv langchain/langchain/utils/json_schema.py core/langchain_core/utils
mv langchain/langchain/utils/html.py core/langchain_core/utils
mv langchain/langchain/utils/strings.py core/langchain_core/utils
cat langchain/langchain/utils/env.py >> core/langchain_core/utils/env.py
rm langchain/langchain/utils/env.py
```

See .scripts/community_split/script_integrations.sh for all changes

libs/community/langchain_community/utilities/brave_search.py

@@ -0,0 +1,72 @@
+import json
+from typing import List
+
+import requests
+from langchain_core.documents import Document
+from langchain_core.pydantic_v1 import BaseModel, Field
+
+
+class BraveSearchWrapper(BaseModel):
+    """Wrapper around the Brave search engine."""
+
+    api_key: str
+    """The API key to use for the Brave search engine."""
+    search_kwargs: dict = Field(default_factory=dict)
+    """Additional keyword arguments to pass to the search request."""
+    base_url: str = "https://api.search.brave.com/res/v1/web/search"
+    """The base URL for the Brave search engine."""
+
+    def run(self, query: str) -> str:
+        """Query the Brave search engine and return the results as a JSON string.
+
+        Args:
+            query: The query to search for.
+
+        Returns: The results as a JSON string.
+
+        """
+        web_search_results = self._search_request(query=query)
+        final_results = [
+            {
+                "title": item.get("title"),
+                "link": item.get("url"),
+                "snippet": item.get("description"),
+            }
+            for item in web_search_results
+        ]
+        return json.dumps(final_results)
+
+    def download_documents(self, query: str) -> List[Document]:
+        """Query the Brave search engine and return the results as a list of Documents.
+
+        Args:
+            query: The query to search for.
+
+        Returns: The results as a list of Documents.
+
+        """
+        results = self._search_request(query)
+        return [
+            Document(
+                page_content=item.get("description"),
+                metadata={"title": item.get("title"), "link": item.get("url")},
+            )
+            for item in results
+        ]
+
+    def _search_request(self, query: str) -> List[dict]:
+        headers = {
+            "X-Subscription-Token": self.api_key,
+            "Accept": "application/json",
+        }
+        req = requests.PreparedRequest()
+        params = {**self.search_kwargs, **{"q": query}}
+        req.prepare_url(self.base_url, params)
+        if req.url is None:
+            raise ValueError("prepared url is None, this should not happen")
+
+        response = requests.get(req.url, headers=headers)
+        if not response.ok:
+            raise Exception(f"HTTP error {response.status_code}")
+
+        return response.json().get("web", {}).get("results", [])