[FEAT] Support OpenVINO NPU device

[szeyu]

Is your feature request related to a problem? Please describe.

Based on Intel OpenVINO docs : Run LLMs with OpenVINO GenAI Flavor on NPU

Now that NPU is available on OpenVINO, not just CPU and GPU

Describe the solution you'd like

Add npu as an option for device run by OpenVINO engine