Add pyhccl (#503)

This is the first step to support trl vllm serve on Ascend NPU
https://github.com/vllm-project/vllm-ascend/issues/459.
This PR can work properly only when
https://github.com/vllm-project/vllm/pull/16464 is merged into vLLM.

---------

Signed-off-by: hzji210@gmail.com <hzji210@gmail.com>

vllm_ascend/distributed/communicator.py

@@ -30,5 +30,6 @@ class NPUCommunicator(DeviceCommunicatorBase):
                  device_group: Optional[ProcessGroup] = None,
                  unique_name: str = ""):
         super().__init__(cpu_group, device, device_group, unique_name)
+        # TODO(hz): Refer to CudaCommunicator's implementation to integrate PyHcclCommunicator
         # init device according to rank
         self.device = torch.npu.current_device()