Passing 'custom' options

[danielfriis]

Thanks for all the work on this gem!

Is there any way to pass options as defined in the OpenAI documentation, but not directly supported by RubyLLM?

Specifically, I want to set the 'store' parameter.

I noticed @parruda has worked on this in #130, which seems like an elegant way to support any options not directly covered by RubyLLM.