Add support for Codex CLI to run evals

## Requirement

Currently the only agent supported is VS Code Copilot. We should add support to Codex CLI.

## Resources

[Codex with Azure OpenAI in Azure AI Foundry Models](https://learn.microsoft.com/en-us/azure/ai-foundry/openai/how-to/codex?tabs=npm)
[GPT-5-Codex Prompting Guide](https://cookbook.openai.com/examples/gpt-5-codex_prompting_guide)