How to fix 401 errors with Gemini embeddings

[Falco]

@m_terenui

I used to have the following url in the configuration of the model for embeddings using gemini (but I got errors) :
https://generativelanguage.googleapis.com/v1beta/models/gemini-embedding-001:embedContent

Looking at documentation in internet, I found that the url should be instead following a pattern like:
https://{zone}-aiplatform.googleapis.com/v1/projects/{google cloud project reference}/locations/{zone}/publishers/google/models/gemini-embedding-001:embedContent

This is Google AI Studio vs Gemini Enterprise Agent Platform (formerly Vertex AI).

For embeddings, we are compatible only with the first one.

We just got a PR to make our LLM inference compatible with the second one, as we were only compatible with the first one for LLMs too.