[Feat] Add Euler xlite graph wrapper support (#4526)

### What this PR does / why we need it?
This patch adds support for the xlite graph wrapper to vllm_ascend.
Xlite provides operator implementations of the transformer network on
Ascend hardware. For details about xlite, please refer to the following
link: https://gitee.com/openeuler/GVirt/blob/master/xlite/README.md
The latest performance comparison data between xlite and the default
aclgraph mode is as follows:

## Qwen3 32B TPS 910B3(A2) Online Inference Performance Comparison
- aclgraph: main(c4a71fc6) 
- xlite-full: main(c4a71fc6) + xlite-full
- xlite-decode-only: main(c4a71fc6) + xlite-decode-only
- diff1: Performance comparison between xlite-full and aclgraph
- diff2: Performance comparison between xlite-decode-only and aclgraph


### Does this PR introduce _any_ user-facing change?
Enable the xlite graph mode by setting xlite_graph_config:
--additional-config='{"xlite_graph_config": {"enabled": true}}' #
Enabled for decode only
--additional-config='{"xlite_graph_config": {"enabled": true,
"full_mode": true}}' # Enabled for prefill and decode

- vLLM version: v0.12.0
- vLLM main:
ad32e3e19c

---------

Signed-off-by: lulina <lina.lulina@huawei.com>
Co-authored-by: wangxiyuan <wangxiyuan1007@gmail.com>

tests/ut/test_platform.py

@@ -32,6 +32,7 @@ class TestNPUPlatform(TestBase):
     def mock_vllm_ascend_config():
         mock_ascend_config = MagicMock()
         mock_ascend_config.torchair_graph_config.enabled = False
+        mock_ascend_config.xlite_graph_config.enabled = False
         mock_ascend_config.enable_shared_expert_dp = False
         return mock_ascend_config
 
@@ -512,6 +513,16 @@ class TestNPUPlatform(TestBase):
             "vllm_ascend.torchair.torchair_worker.NPUTorchairWorker",
         )
 
+        test_ascend_config = TestNPUPlatform.mock_vllm_ascend_config()
+        test_ascend_config.xlite_graph_config.enabled = True
+        mock_init_ascend.return_value = test_ascend_config
+        vllm_config.parallel_config.worker_cls = "auto"
+        self.platform.check_and_update_config(vllm_config)
+        self.assertEqual(
+            vllm_config.parallel_config.worker_cls,
+            "vllm_ascend.xlite.xlite_worker.XliteWorker",
+        )
+
     @patch("vllm_ascend.ascend_config.check_ascend_config")
     @patch("vllm_ascend.ascend_config.init_ascend_config")
     @patch('vllm_ascend.utils.get_ascend_device_type',