Support for OpenAI to Anthropic schema translator

[maciej-tatarski]

When calling with openAI schema on /v1/chat/completions endpoint, gateway crashes with: unsupported API schema: backend={Anthropic 2023-06-01}"

I cannot find in the code a translator from OpenAI schema to Anthropic schema, would be nice to support this use case as well. Let me know if it is something that I can work on.

[ehfd]

As you might know, the Anthropic to OpenAI translator (likely the opposite direction of what you intend) is implemented in #1878, with additional fixes including #1950, #1953.

But I am aware that in https://github.com/envoyproxy/ai-gateway/tree/main/internal/translator, there is an OpenAI Chat Completions to GCP Anthropic translator. This is the same direction, that is not the opposite, and I suppose most of that code could be reused.

[k1chik]

Hi! I'd like to pick this up. I see that the Anthropic → OpenAI direction already landed in #1878, and the existing OpenAI → GCP Anthropic translator in internal/translator/ looks like a solid starting point to reuse. Happy to coordinate if anyone else is actively working on this. :)