### Summary Port the following PRs to GO in this PR https://github.com/infiniflow/ragflow/pull/16420 https://github.com/infiniflow/ragflow/pull/13295
### What problem does this PR solve? Implement OpenAI chat completions in GO POST /api/v1/openai/<chat_id>/chat/completions OpenAI chat cli: internal/development.md ### Type of change - [x] Refactoring