Update to use latest Azure OpenAI SDK and secure bicep for AI Foundry

[paulyuk]

This pull request introduces significant improvements to the Azure Function app and its infrastructure setup for AI chat capabilities. The main changes include a refactor of the Python function app to use the OpenAI SDK directly, configured for Azure OpenAI, enhanced error handling, and new resource provisioning scripts in bicep for secure role assignments and capability host setup.

The conversation history is saved to Azure Table Storage (can be easily changed to another service).

These updates improve reliability, maintainability, and security of the chat service.## Purpose

Does this introduce a breaking change?

[ ] Yes
[x] No

Pull Request Type

What kind of change does this Pull Request introduce?

[ ] Bugfix
[ ] Feature
[x] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[x] Documentation content changes
[ ] Other... Please describe:

How to Test

follow the readme

[pamelafox]

Python looks good