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_transformers/html2text.py

@@ -0,0 +1,56 @@
+from typing import Any, Sequence
+
+from langchain_core.documents import BaseDocumentTransformer, Document
+
+
+class Html2TextTransformer(BaseDocumentTransformer):
+    """Replace occurrences of a particular search pattern with a replacement string
+
+    Arguments:
+        ignore_links: Whether links should be ignored; defaults to True.
+        ignore_images: Whether images should be ignored; defaults to True.
+
+    Example:
+        .. code-block:: python
+            from langchain_community.document_transformers import Html2TextTransformer
+            html2text = Html2TextTransformer()
+            docs_transform = html2text.transform_documents(docs)
+    """
+
+    def __init__(self, ignore_links: bool = True, ignore_images: bool = True) -> None:
+        self.ignore_links = ignore_links
+        self.ignore_images = ignore_images
+
+    def transform_documents(
+        self,
+        documents: Sequence[Document],
+        **kwargs: Any,
+    ) -> Sequence[Document]:
+        try:
+            import html2text
+        except ImportError:
+            raise ImportError(
+                """html2text package not found, please 
+                install it with `pip install html2text`"""
+            )
+
+        # Create a html2text.HTML2Text object and override some properties
+        h = html2text.HTML2Text()
+        h.ignore_links = self.ignore_links
+        h.ignore_images = self.ignore_images
+
+        new_documents = []
+
+        for d in documents:
+            new_document = Document(
+                page_content=h.handle(d.page_content), metadata={**d.metadata}
+            )
+            new_documents.append(new_document)
+        return new_documents
+
+    async def atransform_documents(
+        self,
+        documents: Sequence[Document],
+        **kwargs: Any,
+    ) -> Sequence[Document]:
+        raise NotImplementedError