[Misc] Add SPDX-License-Identifier headers to python source files (#12628)

- **Add SPDX license headers to python source files**
- **Check for SPDX headers using pre-commit**

commit 9d7ef44c3cfb72ca4c32e1c677d99259d10d4745
Author: Russell Bryant <rbryant@redhat.com>
Date:   Fri Jan 31 14:18:24 2025 -0500

    Add SPDX license headers to python source files
    
This commit adds SPDX license headers to python source files as
recommended to
the project by the Linux Foundation. These headers provide a concise way
that is
both human and machine readable for communicating license information
for each
source file. It helps avoid any ambiguity about the license of the code
and can
    also be easily used by tools to help manage license compliance.
    
The Linux Foundation runs license scans against the codebase to help
ensure
    we are in compliance with the licenses of the code we use, including
dependencies. Having these headers in place helps that tool do its job.
    
    More information can be found on ...

vllm/v1/engine/async_llm.py

+# SPDX-License-Identifier: Apache-2.0
+
 import asyncio
 import os
 from typing import AsyncGenerator, List, Mapping, Optional, Type, Union

vllm/v1/engine/core.py

+# SPDX-License-Identifier: Apache-2.0
+
 import pickle
 import queue
 import signal

vllm/v1/engine/core_client.py

+# SPDX-License-Identifier: Apache-2.0
+
 import asyncio
 import os
 import signal

vllm/v1/engine/detokenizer.py

+# SPDX-License-Identifier: Apache-2.0
+
 from dataclasses import dataclass
 from typing import List, Optional, Union
 

vllm/v1/engine/llm_engine.py

+# SPDX-License-Identifier: Apache-2.0
+
 from typing import Dict, List, Mapping, Optional, Type, Union
 
 from typing_extensions import TypeVar

vllm/v1/engine/mm_input_mapper.py

+# SPDX-License-Identifier: Apache-2.0
+
 from typing import Any, Dict, List, Optional
 
 from vllm.config import ModelConfig

vllm/v1/engine/output_processor.py

+# SPDX-License-Identifier: Apache-2.0
+
 import asyncio
 from dataclasses import dataclass
 from typing import Dict, List, Optional

vllm/v1/engine/processor.py

+# SPDX-License-Identifier: Apache-2.0
+
 import time
 from typing import Mapping, Optional, Union
 

vllm/v1/executor/abstract.py

+# SPDX-License-Identifier: Apache-2.0
+
 from typing import Type
 
 from vllm.config import VllmConfig

vllm/v1/executor/multiproc_executor.py

+# SPDX-License-Identifier: Apache-2.0
+
 import os
 import pickle
 import signal

vllm/v1/kv_cache_interface.py

+# SPDX-License-Identifier: Apache-2.0
+
 from dataclasses import dataclass
 from typing import Dict, List
 

vllm/v1/metrics/loggers.py

+# SPDX-License-Identifier: Apache-2.0
+
 import time
 from abc import ABC, abstractmethod
 from typing import List

vllm/v1/metrics/stats.py

+# SPDX-License-Identifier: Apache-2.0
+
 import time
 from dataclasses import dataclass
 from typing import TYPE_CHECKING, List

vllm/v1/outputs.py

+# SPDX-License-Identifier: Apache-2.0
+
 from dataclasses import dataclass
 from typing import Dict, List, Optional
 

vllm/v1/request.py

+# SPDX-License-Identifier: Apache-2.0
+
 import enum
 from typing import TYPE_CHECKING, List, Optional, Union
 

vllm/v1/sample/metadata.py

+# SPDX-License-Identifier: Apache-2.0
+
 from dataclasses import dataclass
 from typing import Dict, List, Optional, Set
 

vllm/v1/sample/ops/penalties.py

+# SPDX-License-Identifier: Apache-2.0
+
 from typing import List, Set, Tuple
 
 import torch

vllm/v1/sample/ops/topk_topp_sampler.py

+# SPDX-License-Identifier: Apache-2.0
+
 from typing import Dict
 
 import torch

vllm/v1/sample/sampler.py

+# SPDX-License-Identifier: Apache-2.0
 """A layer that samples the next tokens from the model's outputs."""
 from typing import Tuple
 

vllm/v1/serial_utils.py

+# SPDX-License-Identifier: Apache-2.0
+
 import pickle