Google Vertex Translation LLM

It would be a great feature to have.

In order to provide native translation support, VertexProvider needs to implement Drupal\ai\OperationType\TranslateText\TranslateTextInterface (which has only one translateText() method)
Implementation can use its own endpoint, different from chat()

Created first working version. Vertex native translation supports 2 modes: Translation LLM (highest quality, limited to 19 languages) and NMT (fastest, works with larger set of languages), see https://cloud.google.com/vertex-ai/generative-ai/docs/translate/translat... for details.
MR in its current state supports only Translation LLM.
Results are promising (as in translation is really fast and has the quality expected from Google translation), but I'd like to support NMT as well before marking MR as ready for review