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/document_loaders/gcs_file.py

@@ -0,0 +1,83 @@
+import os
+import tempfile
+from typing import Callable, List, Optional
+
+from langchain_core.documents import Document
+
+from langchain_community.document_loaders.base import BaseLoader
+from langchain_community.document_loaders.unstructured import UnstructuredFileLoader
+from langchain_community.utilities.vertexai import get_client_info
+
+
+class GCSFileLoader(BaseLoader):
+    """Load from GCS file."""
+
+    def __init__(
+        self,
+        project_name: str,
+        bucket: str,
+        blob: str,
+        loader_func: Optional[Callable[[str], BaseLoader]] = None,
+    ):
+        """Initialize with bucket and key name.
+
+        Args:
+            project_name: The name of the project to load
+            bucket: The name of the GCS bucket.
+            blob: The name of the GCS blob to load.
+            loader_func: A loader function that instantiates a loader based on a
+                file_path argument. If nothing is provided, the
+                UnstructuredFileLoader is used.
+
+        Examples:
+            To use an alternative PDF loader:
+            >> from from langchain_community.document_loaders import PyPDFLoader
+            >> loader = GCSFileLoader(..., loader_func=PyPDFLoader)
+
+            To use UnstructuredFileLoader with additional arguments:
+            >> loader = GCSFileLoader(...,
+            >>      loader_func=lambda x: UnstructuredFileLoader(x, mode="elements"))
+
+        """
+        self.bucket = bucket
+        self.blob = blob
+        self.project_name = project_name
+
+        def default_loader_func(file_path: str) -> BaseLoader:
+            return UnstructuredFileLoader(file_path)
+
+        self._loader_func = loader_func if loader_func else default_loader_func
+
+    def load(self) -> List[Document]:
+        """Load documents."""
+        try:
+            from google.cloud import storage
+        except ImportError:
+            raise ImportError(
+                "Could not import google-cloud-storage python package. "
+                "Please install it with `pip install google-cloud-storage`."
+            )
+
+        # Initialise a client
+        storage_client = storage.Client(
+            self.project_name, client_info=get_client_info("google-cloud-storage")
+        )
+        # Create a bucket object for our bucket
+        bucket = storage_client.get_bucket(self.bucket)
+        # Create a blob object from the filepath
+        blob = bucket.blob(self.blob)
+        # retrieve custom metadata associated with the blob
+        metadata = bucket.get_blob(self.blob).metadata
+        with tempfile.TemporaryDirectory() as temp_dir:
+            file_path = f"{temp_dir}/{self.blob}"
+            os.makedirs(os.path.dirname(file_path), exist_ok=True)
+            # Download the file to a destination
+            blob.download_to_filename(file_path)
+            loader = self._loader_func(file_path)
+            docs = loader.load()
+            for doc in docs:
+                if "source" in doc.metadata:
+                    doc.metadata["source"] = f"gs://{self.bucket}/{self.blob}"
+                if metadata:
+                    doc.metadata.update(metadata)
+            return docs