[8.x] Add OpenAI inference details (#3929)

[lcawl]

Backport

This will backport the following commits from main to 8.x:

• Add OpenAI inference details (#3929)

Questions ?

Please refer to the Backport tool documentation

[github-actions]

Following you can find the validation results for the APIs you have changed.

API	Status	Request	Response
inference.chat_completion_unified	⚪	Missing test	Missing test
inference.completion	⚪	Missing test	Missing test
inference.delete	⚪	Missing test	Missing test
inference.get	🟢	1/1	1/1
inference.put_openai	⚪	Missing test	Missing test
inference.put_watsonx	⚪	Missing test	Missing test
inference.put	⚪	Missing test	Missing test
inference.rerank	⚪	Missing test	Missing test
inference.sparse_embedding	⚪	Missing test	Missing test
inference.stream_completion	⚪	Missing test	Missing test
inference.text_embedding	⚪	Missing test	Missing test
inference.update	⚪	Missing test	Missing test

You can validate these APIs yourself by using the make validate target.