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/openai-functions-tool-retrieval-agent/openai_functions_tool_retrieval_agent/agent.py

@@ -6,13 +6,13 @@ from langchain.agents import (
 )
 from langchain.agents.format_scratchpad import format_to_openai_functions
 from langchain.agents.output_parsers import OpenAIFunctionsAgentOutputParser
-from langchain.schema import Document
 from langchain_community.chat_models import ChatOpenAI
 from langchain_community.embeddings import OpenAIEmbeddings
 from langchain_community.tools.convert_to_openai import format_tool_to_openai_function
 from langchain_community.tools.tavily_search import TavilySearchResults
 from langchain_community.utilities.tavily_search import TavilySearchAPIWrapper
 from langchain_community.vectorstores import FAISS
+from langchain_core.documents import Document
 from langchain_core.messages import AIMessage, HumanMessage
 from langchain_core.prompts import (
     ChatPromptTemplate,