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/embeddings/mlflow_gateway.py

@@ -0,0 +1,75 @@
+from __future__ import annotations
+
+import warnings
+from typing import Any, Iterator, List, Optional
+
+from langchain_core.embeddings import Embeddings
+from langchain_core.pydantic_v1 import BaseModel
+
+
+def _chunk(texts: List[str], size: int) -> Iterator[List[str]]:
+    for i in range(0, len(texts), size):
+        yield texts[i : i + size]
+
+
+class MlflowAIGatewayEmbeddings(Embeddings, BaseModel):
+    """
+    Wrapper around embeddings LLMs in the MLflow AI Gateway.
+
+    To use, you should have the ``mlflow[gateway]`` python package installed.
+    For more information, see https://mlflow.org/docs/latest/gateway/index.html.
+
+    Example:
+        .. code-block:: python
+
+            from langchain_community.embeddings import MlflowAIGatewayEmbeddings
+
+            embeddings = MlflowAIGatewayEmbeddings(
+                gateway_uri="<your-mlflow-ai-gateway-uri>",
+                route="<your-mlflow-ai-gateway-embeddings-route>"
+            )
+    """
+
+    route: str
+    """The route to use for the MLflow AI Gateway API."""
+    gateway_uri: Optional[str] = None
+    """The URI for the MLflow AI Gateway API."""
+
+    def __init__(self, **kwargs: Any):
+        warnings.warn(
+            "`MlflowAIGatewayEmbeddings` is deprecated. Use `MlflowEmbeddings` or "
+            "`DatabricksEmbeddings` instead.",
+            DeprecationWarning,
+        )
+        try:
+            import mlflow.gateway
+        except ImportError as e:
+            raise ImportError(
+                "Could not import `mlflow.gateway` module. "
+                "Please install it with `pip install mlflow[gateway]`."
+            ) from e
+
+        super().__init__(**kwargs)
+        if self.gateway_uri:
+            mlflow.gateway.set_gateway_uri(self.gateway_uri)
+
+    def _query(self, texts: List[str]) -> List[List[float]]:
+        try:
+            import mlflow.gateway
+        except ImportError as e:
+            raise ImportError(
+                "Could not import `mlflow.gateway` module. "
+                "Please install it with `pip install mlflow[gateway]`."
+            ) from e
+
+        embeddings = []
+        for txt in _chunk(texts, 20):
+            resp = mlflow.gateway.query(self.route, data={"text": txt})
+            embeddings.append(resp["embeddings"])
+        return embeddings
+
+    def embed_documents(self, texts: List[str]) -> List[List[float]]:
+        return self._query(texts)
+
+    def embed_query(self, text: str) -> List[float]:
+        return self._query([text])[0]