[langchain-sqlserver] Add support for storing chat history using LangGraph

[yorek]

The latest version (0.3) of LangChain mentions that

As of the v0.3 release of LangChain, we recommend that LangChain users take advantage of LangGraph persistence to incorporate memory into new LangChain applications.

So we should add support to LangGraph persistence API to make the SQL Server LangChain library compatible also with the more powerful LangGraph framework