[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 the SPDX site:
    
    - https://spdx.dev/learn/handling-license-info/

Signed-off-by: Russell Bryant <rbryant@redhat.com>

commit 5a1cf1cb3b80759131c73f6a9dddebccac039dea
Author: Russell Bryant <rbryant@redhat.com>
Date:   Fri Jan 31 14:36:32 2025 -0500

    Check for SPDX headers using pre-commit
Signed-off-by: Russell Bryant <rbryant@redhat.com>

---------
Signed-off-by: Russell Bryant <rbryant@redhat.com>

examples/other/tensorize_vllm_model.py

+# SPDX-License-Identifier: Apache-2.0
+
 import argparse
 import dataclasses
 import json

find_cuda_init.py

+# SPDX-License-Identifier: Apache-2.0
+
 import importlib
 import traceback
 from typing import Callable

python_only_dev.py

+# SPDX-License-Identifier: Apache-2.0
+
 msg = """Old style python only build (without compilation) is deprecated, please check https://docs.vllm.ai/en/latest/getting_started/installation.html#python-only-build-without-compilation for the new way to do python only build (without compilation).
 
 TL;DR:

setup.py

+# SPDX-License-Identifier: Apache-2.0
+
 import ctypes
 import importlib.util
 import logging

tests/async_engine/api_server_async_engine.py

+# SPDX-License-Identifier: Apache-2.0
 """vllm.entrypoints.api_server with some extra logging for testing."""
 from typing import Any, Dict, Iterable
 

tests/async_engine/test_api_server.py

+# SPDX-License-Identifier: Apache-2.0
+
 import subprocess
 import sys
 import time

tests/async_engine/test_async_llm_engine.py

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

tests/async_engine/test_request_tracker.py

+# SPDX-License-Identifier: Apache-2.0
+
 import pytest
 
 from vllm.engine.async_llm_engine import RequestTracker

tests/basic_correctness/test_basic_correctness.py

+# SPDX-License-Identifier: Apache-2.0
 """Compare the short outputs of HF and vLLM when using greedy sampling.
 
 Run `pytest tests/basic_correctness/test_basic_correctness.py`.

tests/basic_correctness/test_chunked_prefill.py

+# SPDX-License-Identifier: Apache-2.0
 """Compare the outputs of HF and vLLM when using greedy sampling.
 
 It tests chunked prefill. Chunked prefill can be enabled by

tests/basic_correctness/test_cpu_offload.py

+# SPDX-License-Identifier: Apache-2.0
+
 from ..utils import compare_two_settings
 
 

tests/basic_correctness/test_cumem.py

+# SPDX-License-Identifier: Apache-2.0
+
 import torch
 
 from vllm import LLM, SamplingParams

tests/basic_correctness/test_preemption.py

+# SPDX-License-Identifier: Apache-2.0
 """Compare the short outputs of HF and vLLM when using greedy sampling.
 
 VLLM_TEST_ENABLE_ARTIFICIAL_PREEMPT=1 has to be set before running this test.

tests/compile/backend.py

+# SPDX-License-Identifier: Apache-2.0
+
 from copy import deepcopy
 from typing import Callable, Union
 

tests/compile/piecewise/test_simple.py

+# SPDX-License-Identifier: Apache-2.0
 """
 Test the piecewise compilation with a simple model so that we
 can exactly calculate the expected output and side effects.

tests/compile/piecewise/test_toy_llama.py

+# SPDX-License-Identifier: Apache-2.0
 """
 Test the piecewise compilation with a simple model, comparing the output
 with and without the piecewise compilation.

tests/compile/test_basic_correctness.py

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

tests/compile/test_full_graph.py

+# SPDX-License-Identifier: Apache-2.0
+
 import pytest
 
 from vllm.config import CompilationLevel

tests/compile/test_functionalization.py

+# SPDX-License-Identifier: Apache-2.0
+
 import pytest
 import torch
 

tests/compile/test_fusion.py

+# SPDX-License-Identifier: Apache-2.0
+
 import pytest
 import torch
 from compressed_tensors.quantization import FP8_DTYPE