Add support for max_completion_tokens in OpenAI chat options request

[dafriz]

New field max_completion_tokens added by OpenAI, is to set an upper bound for the number of tokens that can be generated for a completion, including visible output tokens and reasoning tokens. Replaces max_tokens field which is now deprecated.

max_completion_tokens works on all models but max_tokens doesn't work on the new models - o1-mini etc

https://platform.openai.com/docs/api-reference/chat/create#chat-create-max_completion_tokens

[markpollack]

max_tokens
Deprecated
integer or null

Optional
The maximum number of [tokens](https://platform.openai.com/tokenizer) that can be generated in the chat completion. This value can be used to control [costs](https://openai.com/api/pricing/) for text generated via API.

This value is now deprecated in favor of max_completion_tokens, and is not compatible with [o1 series models](https://platform.openai.com/docs/guides/reasoning).

for reference

[tzolov]

resolved by f56ce20