[aclgraph] implentment NPUPiecewiseBackend to enable aclgraph (#836)

### What this PR does / why we need it?
1. Implentment `NPUPiecewiseBackend` to enable aclgraph
2. Eable aclgraph by default in V1, but raise error when running
deepseek and raise warning when running models except for qwen

### How was this patch tested?
CI pass with the new ut

---------

Signed-off-by: MengqingCao <cmq0113@163.com>

tests/multicard/test_dynamic_npugraph_batchsize.py

@@ -18,8 +18,7 @@ import pytest
 import torch
 from vllm import LLM, SamplingParams
 
-# TODO: revert me when cuda hard code is fixed in 'VllmBackend'
-torch.cuda.CUDAGraph = torch.npu.NPUGraph
+from vllm_ascend.utils import vllm_version_is
 
 MODELS = [
     "Qwen/Qwen2.5-0.5B-Instruct",
@@ -33,6 +32,9 @@ prompts = [
 ]
 
 
+@pytest.mark.skipif(
+    (vllm_version_is("0.8.5") or vllm_version_is("0.8.5.post1")),
+    reason="aclgraph not supported in v0.8.5 and v0.8.5.post1")
 @pytest.mark.parametrize("model", MODELS)
 @pytest.mark.parametrize("tp_size", TENSOR_PARALLELS)
 @pytest.mark.parametrize("max_tokens", [64])