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/neo4j-generation/neo4j_generation/chain.py

@@ -3,10 +3,10 @@ from typing import List, Optional
 from langchain.chains.openai_functions import (
     create_structured_output_chain,
 )
-from langchain.schema import Document
 from langchain_community.chat_models import ChatOpenAI
 from langchain_community.graphs import Neo4jGraph
 from langchain_community.graphs.graph_document import GraphDocument
+from langchain_core.documents import Document
 from langchain_core.prompts import ChatPromptTemplate
 
 from neo4j_generation.utils import (