Refactor Azure client initialization to reduce code duplication

[ylnsnv]

Changes being requested

This PR streamlines the initialization process for AzureOpenAI and AsyncAzureOpenAI clients by centralizing common configuration steps. The main change involves the introduction of a _configure_client_settings method in BaseAzureClient, which handles the setup of API keys, tokens, and endpoints.

Key Changes:

• Centralized configuration logic in BaseAzureClient.
• Updated AzureOpenAI and AsyncAzureOpenAI to use the new configuration method.
• Improved error handling for configuration parameters.

Benefits:

• Reduces repetitive code across client classes.
• Simplifies future updates and maintenance of the initialization process.

This update enhances the code's clarity and maintainability without introducing breaking changes.

Additional context & links

[gleason-m]

I'm not able to mark comments as Unresolved, so putting my feedback to your iteration in a separate comment:

Ahh, no you still want to check the env var, just raise the error if api_verison isn't provided and there is no env var set. Here's the original init snippet:

if api_version is None:
    api_version = os.environ.get("OPENAI_API_VERSION"

if api_version is None:
    raise ValueError(
        "Must provide either the `api_version` argument or the `OPENAI_API_VERSION` environment variable"
    )