openai api base support

[sweep-ai[bot]]

Apply Sweep Rules to your PR?

• [ ] Apply: All docstrings and comments should be up to date.
• [ ] Apply: Do not include large chunks of commented out code.
• [ ] Apply: Ensure that all error logs use traceback during exceptions.
• [ ] Apply: Avoid using import pdb; pdb.set_trace() in production code.
• [ ] Apply: Avoid using debug log or print statements in production code.
• [ ] Apply: Ensure that code is properly formatted and follows consistent styling guidelines.

[bdqfork]

This is a necessary feature when direct access to OpenAI is not possible. @Czechh