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/couchbase.py

@@ -0,0 +1,100 @@
+import logging
+from typing import Iterator, List, Optional
+
+from langchain_core.documents import Document
+
+from langchain_community.document_loaders.base import BaseLoader
+
+logger = logging.getLogger(__name__)
+
+
+class CouchbaseLoader(BaseLoader):
+    """Load documents from `Couchbase`.
+
+    Each document represents one row of the result. The `page_content_fields` are
+    written into the `page_content`of the document. The `metadata_fields` are written
+    into the `metadata` of the document. By default, all columns are written into
+    the `page_content` and none into the `metadata`.
+    """
+
+    def __init__(
+        self,
+        connection_string: str,
+        db_username: str,
+        db_password: str,
+        query: str,
+        *,
+        page_content_fields: Optional[List[str]] = None,
+        metadata_fields: Optional[List[str]] = None,
+    ) -> None:
+        """Initialize Couchbase document loader.
+
+        Args:
+            connection_string (str): The connection string to the Couchbase cluster.
+            db_username (str): The username to connect to the Couchbase cluster.
+            db_password (str): The password to connect to the Couchbase cluster.
+            query (str): The SQL++ query to execute.
+            page_content_fields (Optional[List[str]]): The columns to write into the
+                `page_content` field of the document. By default, all columns are
+                written.
+            metadata_fields (Optional[List[str]]): The columns to write into the
+                `metadata` field of the document. By default, no columns are written.
+        """
+        try:
+            from couchbase.auth import PasswordAuthenticator
+            from couchbase.cluster import Cluster
+            from couchbase.options import ClusterOptions
+        except ImportError as e:
+            raise ImportError(
+                "Could not import couchbase package."
+                "Please install couchbase SDK with `pip install couchbase`."
+            ) from e
+        if not connection_string:
+            raise ValueError("connection_string must be provided.")
+
+        if not db_username:
+            raise ValueError("db_username must be provided.")
+
+        if not db_password:
+            raise ValueError("db_password must be provided.")
+
+        auth = PasswordAuthenticator(
+            db_username,
+            db_password,
+        )
+
+        self.cluster: Cluster = Cluster(connection_string, ClusterOptions(auth))
+        self.query = query
+        self.page_content_fields = page_content_fields
+        self.metadata_fields = metadata_fields
+
+    def load(self) -> List[Document]:
+        """Load Couchbase data into Document objects."""
+        return list(self.lazy_load())
+
+    def lazy_load(self) -> Iterator[Document]:
+        """Load Couchbase data into Document objects lazily."""
+        from datetime import timedelta
+
+        # Ensure connection to Couchbase cluster
+        self.cluster.wait_until_ready(timedelta(seconds=5))
+
+        # Run SQL++ Query
+        result = self.cluster.query(self.query)
+        for row in result:
+            metadata_fields = self.metadata_fields
+            page_content_fields = self.page_content_fields
+
+            if not page_content_fields:
+                page_content_fields = list(row.keys())
+
+            if not metadata_fields:
+                metadata_fields = []
+
+            metadata = {field: row[field] for field in metadata_fields}
+
+            document = "\n".join(
+                f"{k}: {v}" for k, v in row.items() if k in page_content_fields
+            )
+
+            yield (Document(page_content=document, metadata=metadata))