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/base.py

@@ -0,0 +1,102 @@
+"""Abstract interface for document loader implementations."""
+from __future__ import annotations
+
+from abc import ABC, abstractmethod
+from typing import TYPE_CHECKING, Iterator, List, Optional
+
+from langchain_core.documents import Document
+
+from langchain_community.document_loaders.blob_loaders import Blob
+
+if TYPE_CHECKING:
+    from langchain.text_splitter import TextSplitter
+
+
+class BaseLoader(ABC):
+    """Interface for Document Loader.
+
+    Implementations should implement the lazy-loading method using generators
+    to avoid loading all Documents into memory at once.
+
+    The `load` method will remain as is for backwards compatibility, but its
+    implementation should be just `list(self.lazy_load())`.
+    """
+
+    # Sub-classes should implement this method
+    # as return list(self.lazy_load()).
+    # This method returns a List which is materialized in memory.
+    @abstractmethod
+    def load(self) -> List[Document]:
+        """Load data into Document objects."""
+
+    def load_and_split(
+        self, text_splitter: Optional[TextSplitter] = None
+    ) -> List[Document]:
+        """Load Documents and split into chunks. Chunks are returned as Documents.
+
+        Args:
+            text_splitter: TextSplitter instance to use for splitting documents.
+              Defaults to RecursiveCharacterTextSplitter.
+
+        Returns:
+            List of Documents.
+        """
+        from langchain.text_splitter import RecursiveCharacterTextSplitter
+
+        if text_splitter is None:
+            _text_splitter: TextSplitter = RecursiveCharacterTextSplitter()
+        else:
+            _text_splitter = text_splitter
+        docs = self.load()
+        return _text_splitter.split_documents(docs)
+
+    # Attention: This method will be upgraded into an abstractmethod once it's
+    #            implemented in all the existing subclasses.
+    def lazy_load(
+        self,
+    ) -> Iterator[Document]:
+        """A lazy loader for Documents."""
+        raise NotImplementedError(
+            f"{self.__class__.__name__} does not implement lazy_load()"
+        )
+
+
+class BaseBlobParser(ABC):
+    """Abstract interface for blob parsers.
+
+    A blob parser provides a way to parse raw data stored in a blob into one
+    or more documents.
+
+    The parser can be composed with blob loaders, making it easy to reuse
+    a parser independent of how the blob was originally loaded.
+    """
+
+    @abstractmethod
+    def lazy_parse(self, blob: Blob) -> Iterator[Document]:
+        """Lazy parsing interface.
+
+        Subclasses are required to implement this method.
+
+        Args:
+            blob: Blob instance
+
+        Returns:
+            Generator of documents
+        """
+
+    def parse(self, blob: Blob) -> List[Document]:
+        """Eagerly parse the blob into a document or documents.
+
+        This is a convenience method for interactive development environment.
+
+        Production applications should favor the lazy_parse method instead.
+
+        Subclasses should generally not over-ride this parse method.
+
+        Args:
+            blob: Blob instance
+
+        Returns:
+            List of documents
+        """
+        return list(self.lazy_parse(blob))