Add GPT support for Azure OpenAI

Eventually we will need to support the Azure instance for OpenAI. Looking at the [Azure Quickstart](https://learn.microsoft.com/en-us/azure/ai-services/openai/quickstart?tabs=bash%2Cpython&pivots=rest-api), this should be relatively straightforward (simply calling the appropriate endpoint URL).

Start by locating the existing OpenAI integration and compare its request endpoint with the Azure Quickstart linked in the issue. Confirm how Azure instance configuration is represented and verify that requests work against the appropriate Azure endpoint; the issue provides no named files or tests.

Written by the indexing model from the issue text.