Add support for Gemini models

[rajasbansal]

Is your feature request related to a problem? Please describe.
We have seen new support for gemini models from the google https://ai.google.dev/. The performance seems better than the PaLM model. We should add support for Gemini as a provider and also benchmark the model to get a better idea.

Describe the solution you'd like
Add support for gemini as a a new model similar to PaLM https://github.com/refuel-ai/autolabel/blob/main/src/autolabel/models/palm.py. Bechmark the performance on datasets mentioned here https://www.refuel.ai/blog-posts/llm-labeling-technical-report or https://www.refuel.ai/blog-posts/announcing-refuel-llm

[rajasbansal]

Gemma (https://blog.google/technology/developers/gemma-open-models/?utm_source=x&utm_medium=organicsocial&utm_campaign=gdm&utm_content=) or Mistral/Mixtral (https://mistral.ai/news/announcing-mistral-7b/) could also be interesting additions