feat: add more configuration and fix import path

[ariefwijaya]

• feat(example script):
  • Add option to use ENDPOINT_URL to run locally before deploying to RunPod
  • Add validation to ensure API_KEY is only valid for RunPod
• feat:
  • Add more configuration options for VLLM deployment, such as SERVED_MODEL_NAME, etc.
• fix:
  • Change .model to model in the import path, since .model causes an error