Spring-ai Add completion_tokens_details with reasoning_tokens to OpenAi Usage

Added the New fields added by OpenAI to the Usage response

OpenAI Docs reference - https://platform.openai.com/docs/api-reference/chat/object#chat/object-usage-completion_tokens_details__table

This resolves https://github.com/spring-projects/spring-ai/issues/1369 but is also useful for those wanting to access reasoning_tokens usage I.e those using o1-mini model.

Comment From: markpollack

Created issue https://github.com/spring-projects/spring-ai/issues/1407 to track how to expose 'non-standard' Usage fields in the portable API

Comment From: markpollack

thanks! merged in 1673907db09a6cff72439ce62f87450d4deac977