text: Title: Add Vertex AI Integration
  Body: **Is your feature request related to a problem? Please describe.**
  No Vertex AI support
  
  **Describe the solution you'd like**
  Add a new LLM class that integrates Vertex AI, Langchain [docs](https://python.langchain.com/v0.2/docs/integrations/chat/google_vertex_ai_palm/)
  
  **Describe alternatives you've considered**
  Directly pass the model_instance in the graph_config, like [here](https://github.com/VinciGit00/Scrapegraph-ai/blob/main/examples/azure/smart_scraper_azure.py)
  
  