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/docstore/in_memory.py

@@ -0,0 +1,50 @@
+"""Simple in memory docstore in the form of a dict."""
+from typing import Dict, List, Optional, Union
+
+from langchain_core.documents import Document
+
+from langchain_community.docstore.base import AddableMixin, Docstore
+
+
+class InMemoryDocstore(Docstore, AddableMixin):
+    """Simple in memory docstore in the form of a dict."""
+
+    def __init__(self, _dict: Optional[Dict[str, Document]] = None):
+        """Initialize with dict."""
+        self._dict = _dict if _dict is not None else {}
+
+    def add(self, texts: Dict[str, Document]) -> None:
+        """Add texts to in memory dictionary.
+
+        Args:
+            texts: dictionary of id -> document.
+
+        Returns:
+            None
+        """
+        overlapping = set(texts).intersection(self._dict)
+        if overlapping:
+            raise ValueError(f"Tried to add ids that already exist: {overlapping}")
+        self._dict = {**self._dict, **texts}
+
+    def delete(self, ids: List) -> None:
+        """Deleting IDs from in memory dictionary."""
+        overlapping = set(ids).intersection(self._dict)
+        if not overlapping:
+            raise ValueError(f"Tried to delete ids that does not  exist: {ids}")
+        for _id in ids:
+            self._dict.pop(_id)
+
+    def search(self, search: str) -> Union[str, Document]:
+        """Search via direct lookup.
+
+        Args:
+            search: id of a document to search for.
+
+        Returns:
+            Document if found, else error message.
+        """
+        if search not in self._dict:
+            return f"ID {search} not found."
+        else:
+            return self._dict[search]