Add retry logic to OpenAI API queries to increase Chat tenacity

- Move completion and chat_completion into helper methods under utils.py
- Add retry with exponential backoff on OpenAI exceptions using
  tenacity package. This is officially suggested and used by other
  popular GPT based libraries

pyproject.toml

@@ -42,6 +42,7 @@ dependencies = [
     "jinja2 == 3.1.2",
     "openai >= 0.27.0",
     "tiktoken >= 0.3.0",
+    "tenacity >= 8.2.2",
     "pillow == 9.3.0",
     "pydantic == 1.9.1",
     "pyqt6 == 6.3.1",