[Scenario]: Add sample to show private networking from APIM to Azure Open AI (AOAI)

### Describe the scenario

Sample should demonstrate how to configure private networking to ensure the connectivity from APIM to AOAI is happening over private endpoint

### Improvement to Project

From what I've seen this is a struggle for a lot of implementations, so I believe having this sample out there would help the community to have a known working solution

### Are you able to collaborate and/or submit a pull request?

Yes