Adding Gemini as translator backend

[dgoryeo]

Gemini would be a good fit for Cerlancism translator since it provides much larger window size than GPT. Would you consider to add Gemini 1.5 pro as an engine?

[Cerlancism]

You should able to do it by just overriding the OPENAI_BASE_URL env

Documentation from Google appears to provide such endpoints:

https://cloud.google.com/vertex-ai/generative-ai/docs/multimodal/call-vertex-using-openai-library

[Cerlancism]

Or run your own proxy: https://github.com/zhu327/gemini-openai-proxy