OpenAI Model Configuration Steps

[teresaqhoang]

Motivation and Context

1. Split setup in Sample 4 into two separate configuration steps for Completion and Embeddings models
2. Hooked up oai and aoai APIs to load models into dropdown

Description

1. new component ModelConfig that makes API call to load and populate models / deployments into dropdown using key and endpoint where applicable
2. State changes to maintain values between tab transitions
   
   

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows SK Contribution Guidelines (https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md)
• The code follows the .NET coding conventions (https://learn.microsoft.com/dotnet/csharp/fundamentals/coding-style/coding-conventions) verified with dotnet format
• All unit tests pass, and I have added new tests where possible
• I didn't break anyone 😄