Choose LLM in developer settings

[jeannot-prvlimburg]

This issue is for a: (mark with an x)

- [ ] bug report -> please search issues before submitting
- [x ] feature request
- [ ] documentation issue or request
- [ ] regression (a behavior that used to work and stopped in a new release)

Expected/desired behavior

Add a setting in the developer settings tab to select the underlying LLM (e.g. GPT-3.5 or GPT-4o)

[pamelafox]

If you would like to implement that yourself, this PR shows the general changes I make when adding a new setting: https://github.com/Azure-Samples/azure-search-openai-demo/pull/1814/files

[jeannot-prvlimburg]

If you would like to implement that yourself, this PR shows the general changes I make when adding a new setting: https://github.com/Azure-Samples/azure-search-openai-demo/pull/1814/files

Thanks! I’ll give it a try.