Add per-request GCP Vertex AI safety settings to the existing OpenAI-compatible Gemini chat-completions…

Add per-request GCP Vertex AI safety settings to the existing OpenAI-compatible Gemini chat-completions…: a task in MiMo-V2.6-RL-harbor-code: MiMo-V2.6-RL Code (Harbor) (Harbor dataset). Accept a safetySettings array in the same GCP Vertex AI vendor extension, using Vertex's request schema: each…