Add azure openai services client support

[lucinvitae]

This PR adds support for using Azure OpenAI Services deployments instead of directly calling OpenAI. I was testing out this tool, and figured I would push the change upstream in case the maintainers want to support Azure integrations from potential future users. See the readme for additional instructions.

[cmungall]

Thanks!

We are thinking of using https://github.com/BerriAI/litellm for this kind of thing in future, see #15

However we appreciate it's an issue having another server running so I think we can merge this

[lucinvitae]

@cmungall sure thing! This (CurateGPT) is an exciting project, and I was happy to test it out.

Note: To get e2e ask commands working with the llm lib for my use case, I noticed that I needed to add some additional configuration (in extra-openai-models.yaml), and support for the azure deployment name. See:

• Deployment name support for Azure client lucinvitae/llm#1
• Add forked llm lib with Azure support lucinvitae/curate-gpt#2

Setting the deployment name isn't required in most cases. The current latest llm lib version may work out-of-the-box if the Azure deployment identifier is identical to the model name, but that was not the case for us.