[ckpt] feat: add Hccl ckpt engine backend

[hanhan-networking]

What does this PR do?

Based on ckpt engine abstraction #4775 , in this pr, we add hccl backend to support huawei Ascend npu.

TODO:

• Give more detailed performance testing results.
• Improve checkpoint engine README.

In the near future, we will

• Add Mooncake transfer engine to support p2p communication both for npu and GPU.
• Integrate kimi ckpt engine for more complex communication. For now, the basic functions are tested, we will provide some performance results.

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[CLAassistant]

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[gemini-code-assist]

Code Review

This pull request introduces an HCCLCheckpointEngine backend to support checkpointing on Huawei Ascend NPUs, building upon the existing checkpoint engine abstraction. The changes include the engine implementation, utility functions for creating stateless process groups with IPv6 support, and a new test suite for the HCCL engine. My review primarily focuses on resource management within the new engine, where I've identified a significant resource leak related to ZMQ and socket handling. The provided feedback includes specific suggestions to rectify this issue.

[wuxibin89]

Please format code according to: https://github.com/volcengine/verl/blob/main/CONTRIBUTING.md#code-linting-and-formatting

[hanhan-networking]

Please format code according to: https://github.com/volcengine/verl/blob/main/CONTRIBUTING.md#code-linting-and-formatting

Thank you for kind review, I have fixed the pre-commit comments.