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-gpt-crawler/rag_gpt_crawler/chain.py

@@ -1,11 +1,11 @@
 import json
 from pathlib import Path
 
-from langchain.schema import Document
 from langchain.text_splitter import RecursiveCharacterTextSplitter
 from langchain_community.chat_models import ChatOpenAI
 from langchain_community.embeddings import OpenAIEmbeddings
 from langchain_community.vectorstores import Chroma
+from langchain_core.documents import Document
 from langchain_core.output_parsers import StrOutputParser
 from langchain_core.prompts import ChatPromptTemplate
 from langchain_core.pydantic_v1 import BaseModel