Add Azure AI Content Understanding Sample

[jamesmcroft]

Summary

Add a new code sample demonstrating the usage of the Azure AI Content Understanding service, highlighting how to leverage its capabilities programmatically through APIs.

Description

This feature will introduce a sample to the repo that illustrates how to effectively utilize the new Azure AI Content Understanding service. The sample will guide developers through the process of setting up the Content Understanding service, making REST API calls as outlined in the Microsoft Docs, and integrating these capabilities into document processing workflows. By providing practical, coded examples, the sample will help solve common challenges related to automated content extraction.