docs, templates: update schema imports to core (#17885)

- chat models, messages
- documents
- agentaction/finish
- baseretriever,document
- stroutputparser
- more messages
- basemessage
- format_document
- baseoutputparser

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Co-authored-by: Bagatur <baskaryan@gmail.com>

templates/rag-self-query/rag_self_query/chain.py

@@ -3,11 +3,11 @@ from operator import itemgetter
 from typing import List, Tuple
 
 from langchain.retrievers import SelfQueryRetriever
-from langchain.schema import format_document
 from langchain_community.chat_models import ChatOpenAI
 from langchain_community.embeddings import OpenAIEmbeddings
 from langchain_community.vectorstores.elasticsearch import ElasticsearchStore
 from langchain_core.output_parsers import StrOutputParser
+from langchain_core.prompts import format_document
 from langchain_core.pydantic_v1 import BaseModel, Field
 from langchain_core.runnables import RunnableParallel, RunnablePassthrough