feat: Add webmethod for deleting openai responses (#2160)

# What does this PR do?
This PR creates a webmethod for deleting open AI responses, adds and
implementation for it and makes an integration test for the OpenAI
delete response method.

[//]: # (If resolving an issue, uncomment and update the line below)
# (Closes #2077)

## Test Plan
Ran the standard tests and the pre-commit hooks and the unit tests.

# (## Documentation)
For this pr I made the routes and implementation based on the current
get and create methods. The unit tests were not able to handle this test
due to the mock interface in use, which did not allow for effective CRUD
to be tested. I instead created an integration test to match the
existing ones in the test_openai_responses.

docs/openapi_generator/pyopenapi/utility.py

@@ -156,7 +156,7 @@ def _validate_api_delete_method_returns_none(method) -> str | None:
     
     # Allow OpenAI endpoints to return response objects since they follow OpenAI specification
     method_name = getattr(method, '__name__', '')
-    if method_name.startswith('openai_'):
+    if method_name.__contains__('openai_'):
         return None
     
     if return_type is not None and return_type is not type(None):