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/fauna.py

@@ -0,0 +1,65 @@
+from typing import Iterator, List, Optional, Sequence
+
+from langchain_core.documents import Document
+
+from langchain_community.document_loaders.base import BaseLoader
+
+
+class FaunaLoader(BaseLoader):
+    """Load from `FaunaDB`.
+
+    Attributes:
+        query (str): The FQL query string to execute.
+        page_content_field (str): The field that contains the content of each page.
+        secret (str): The secret key for authenticating to FaunaDB.
+        metadata_fields (Optional[Sequence[str]]):
+            Optional list of field names to include in metadata.
+    """
+
+    def __init__(
+        self,
+        query: str,
+        page_content_field: str,
+        secret: str,
+        metadata_fields: Optional[Sequence[str]] = None,
+    ):
+        self.query = query
+        self.page_content_field = page_content_field
+        self.secret = secret
+        self.metadata_fields = metadata_fields
+
+    def load(self) -> List[Document]:
+        return list(self.lazy_load())
+
+    def lazy_load(self) -> Iterator[Document]:
+        try:
+            from fauna import Page, fql
+            from fauna.client import Client
+            from fauna.encoding import QuerySuccess
+        except ImportError:
+            raise ImportError(
+                "Could not import fauna python package. "
+                "Please install it with `pip install fauna`."
+            )
+        # Create Fauna Client
+        client = Client(secret=self.secret)
+        # Run FQL Query
+        response: QuerySuccess = client.query(fql(self.query))
+        page: Page = response.data
+        for result in page:
+            if result is not None:
+                document_dict = dict(result.items())
+                page_content = ""
+                for key, value in document_dict.items():
+                    if key == self.page_content_field:
+                        page_content = value
+                document: Document = Document(
+                    page_content=page_content,
+                    metadata={"id": result.id, "ts": result.ts},
+                )
+                yield document
+        if page.after is not None:
+            yield Document(
+                page_content="Next Page Exists",
+                metadata={"after": page.after},
+            )