docs, community[patch], experimental[patch], langchain[patch], cli[pa… (#15412)

…tch]: import models from community

ran
```bash
git grep -l 'from langchain\.chat_models' | xargs -L 1 sed -i '' "s/from\ langchain\.chat_models/from\ langchain_community.chat_models/g"
git grep -l 'from langchain\.llms' | xargs -L 1 sed -i '' "s/from\ langchain\.llms/from\ langchain_community.llms/g"
git grep -l 'from langchain\.embeddings' | xargs -L 1 sed -i '' "s/from\ langchain\.embeddings/from\ langchain_community.embeddings/g"
git checkout master libs/langchain/tests/unit_tests/llms
git checkout master libs/langchain/tests/unit_tests/chat_models
git checkout master libs/langchain/tests/unit_tests/embeddings/test_imports.py
make format
cd libs/langchain; make format
cd ../experimental; make format
cd ../core; make format
```

templates/rag-multi-index-router/rag_multi_index_router/chain.py

@@ -1,7 +1,6 @@
 from operator import itemgetter
 from typing import Literal
 
-from langchain.chat_models import ChatOpenAI
 from langchain.output_parsers.openai_functions import PydanticAttrOutputFunctionsParser
 from langchain.prompts import ChatPromptTemplate
 from langchain.retrievers import (
@@ -12,6 +11,7 @@ from langchain.retrievers import (
 )
 from langchain.schema import StrOutputParser
 from langchain.utils.openai_functions import convert_pydantic_to_openai_function
+from langchain_community.chat_models import ChatOpenAI
 from langchain_core.pydantic_v1 import BaseModel, Field
 from langchain_core.runnables import (
     RouterRunnable,