NLQ-to-VDS Tool

[stephenlprice]

Convert the NLQ-to-VDS prompt into a langchain tool - https://python.langchain.com/v0.1/docs/modules/model_io/chat/function_calling/

why?

1. This will allow us to build a true agentic workflow as opposed to the static chain implementation that we have right now.
2. This should help reduce hallucination and generation of incorretly-syntaxed JSON

Definition of Done
I can define an agent using Langchain's react_agent class, and I can declare nlq-to-vds as an available tool. I can pass a natural language query and Tableau Published Data Source metadata to the ReAct agent. The agent will invoke the nlq-to-vds tool and output syntactically correct structured JSON that could be passed through the query-datasource endpoint exposed by VizQL Data Service.