[FEATURE] Add support for Google Gemini API

[boapps]

Is your feature request related to a problem? Please describe.
Google AI models can be used with their genai library. I think it would be nice to have support for this as an alternative API.

Describe the solution you'd like
Add a new GoogleAILLM which allows using their API platform as an LLM.

Describe alternatives you've considered
I know it's possible to use Vertex AI, but if I understand it correctly that's mostly for enterprise uses. While this is more for hobby projects. Also has different pricing.

Additional context
I'll have an attempt at this, expect a PR soon.

[davidberenstein1957]

@boapps this would be a great contribution is you have time to work on this :)

[boapps]

Sorry, I didn't have time for this, but now the gemini api has an OpenAI compatible api as well, so implementation of a new LLM class should be easier. Or it's now also possible to just use the OpenAILLM class with gemini's base url.