[Feature] support eager mode in model runner v2 (#5210)

### What this PR does / why we need it?
#5051 only implement a basic framework for model runner v2, but there
are still some bugs for e2e functionality, this PR aim to enable basic
functionality.
model runner v2 plans:
https://github.com/vllm-project/vllm-ascend/issues/5208

- vLLM version: release/v0.13.0
- vLLM main:
ad32e3e19c
---------
Signed-off-by: Ronald1995 <ronaldautomobile@163.com>

vllm_ascend/worker/v2/sample/sampler.py

@@ -0,0 +1,58 @@
+# Adapt from https://github.com/vllm-project/vllm/blob/main/vllm/v1/worker/gpu/sample/sampler.py.
+# Copyright (c) 2025 Huawei Technologies Co., Ltd. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# This file is a part of the vllm-ascend project.
+#
+
+import torch
+from vllm.v1.sample.ops.topk_topp_sampler import apply_top_k_top_p
+from vllm.v1.worker.gpu.sample.metadata import SamplingMetadata
+from vllm.v1.worker.gpu.sample.min_p import apply_min_p
+from vllm.v1.worker.gpu.sample.sampler import Sampler
+
+from vllm_ascend.worker.v2.sample.gumbel import gumbel_sample
+from vllm_ascend.worker.v2.sample.penalties import \
+    apply_penalties_and_temperature
+
+
+class AscendSampler(Sampler):
+
+    def sample(
+        self,
+        logits: torch.Tensor,
+        sampling_metadata: SamplingMetadata,
+    ) -> tuple[torch.Tensor, torch.Tensor]:
+        """Override sample method because we need to override triton operators
+        called in the method.
+        """
+        # Copy logits to a new FP32 tensor.
+        logits = torch.empty_like(logits, dtype=torch.float32).copy_(logits)
+
+        # Apply penalties and temperature in place.
+        apply_penalties_and_temperature(logits, sampling_metadata)
+        # Apply min_p in place.
+        if sampling_metadata.min_p is not None:
+            apply_min_p(logits, sampling_metadata.min_p)
+        # Apply top_k and/or top_p. This might return a new tensor.
+        logits = apply_top_k_top_p(logits, sampling_metadata.top_k,
+                                   sampling_metadata.top_p)
+
+        sampled = gumbel_sample(
+            logits,
+            sampling_metadata.temperature,
+            sampling_metadata.seeds,
+            sampling_metadata.pos,
+            apply_temperature=False,
+        )
+        return sampled, logits