[Feature]: Support sleep mode in vllm-ascend

[zhuo97]

🚀 The feature, motivation and pitch

In openRLHF, we have a need to put vllm in sleep mode, but vllm-ascend doesn't support this function right now.
Reference: vllm-project/vllm#11743

Alternatives

No response

Additional context

No response

[celestialli]

Thanks for the feedback, since this feature in vLLM relys on cumem of CUDA. Not sure whether Ascend NPU has a library with similar function. We'll check soon.

[wangxiyuan]

complete