Add support for tools in Gemini OpenAI adapter

[yahor-filipchyk]

Hi there! I see that tools, and WebSearch specifically, are already supported in the OpenAI client (i.e., through the createChatWebSearchCompletion, although a streaming version would be even better, is there one?). But looks like not quite in the Gemini adapter. See the TODOs here.

We'd primarily want to use Gemini with "grounding", and I guess I could call the GeminiService directly, but I like the OpenAI adapters and the easy use of multiple providers with a model-based routing.

Thanks!

[peterbanda]

Yeah that makes sense, would like to use Gemini-based tools also for our projects but not sure how it can be hidden / unified under OpenAI interfaces without too much loss. Will check late August.