[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>

tests/kernels/test_awq.py

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

tests/kernels/test_awq_marlin.py

+# SPDX-License-Identifier: Apache-2.0
 """Test AWQ with fused MoE Marlin kernels.
 
 Run `pytest tests/kernels/test_awq_marlin.py`.

tests/kernels/test_awq_triton.py

+# SPDX-License-Identifier: Apache-2.0
 """Tests for the AWQ Triton kernel.
 
 Run `pytest tests/kernels/test_awq_triton.py`.

tests/kernels/test_block_fp8.py

+# SPDX-License-Identifier: Apache-2.0
+
 # Adapted from https://github.com/sgl-project/sglang/pull/2575
 import itertools
 

tests/kernels/test_blocksparse_attention.py

+# SPDX-License-Identifier: Apache-2.0
+
 import random
 from typing import List, Optional, Tuple
 

tests/kernels/test_cache.py

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

tests/kernels/test_cascade_flash_attn.py

+# SPDX-License-Identifier: Apache-2.0
+
 from typing import List, Optional, Tuple
 
 import pytest

tests/kernels/test_causal_conv1d.py

+# SPDX-License-Identifier: Apache-2.0
+
 from typing import Optional
 
 import pytest

tests/kernels/test_cutlass.py

+# SPDX-License-Identifier: Apache-2.0
 """Tests for cutlass kernels
 
 Run `pytest tests/kernels/test_cutlass.py`.

tests/kernels/test_cutlass_2of4_sparse.py

+# SPDX-License-Identifier: Apache-2.0
 """Tests for sparse cutlass kernels
 
 Run `pytest tests/kernels/test_semi_structured.py`.

tests/kernels/test_encoder_decoder_attn.py

+# SPDX-License-Identifier: Apache-2.0
 """
 Tests:
 

tests/kernels/test_flash_attn.py

+# SPDX-License-Identifier: Apache-2.0
+
 from typing import List, Optional, Tuple
 
 import pytest

tests/kernels/test_flashinfer.py

+# SPDX-License-Identifier: Apache-2.0
+
 from typing import List, Optional, Tuple
 
 import flashinfer

tests/kernels/test_fp8_quant.py

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

tests/kernels/test_fused_quant_layernorm.py

+# SPDX-License-Identifier: Apache-2.0
+
 from typing import Optional, Tuple, Union
 
 import pytest

tests/kernels/test_ggml.py

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

tests/kernels/test_gguf.py

+# SPDX-License-Identifier: Apache-2.0
+
 from pathlib import Path
 from typing import List
 

tests/kernels/test_gptq.py

+# SPDX-License-Identifier: Apache-2.0
+
 import torch
 
 from tests.kernels.utils import opcheck

tests/kernels/test_int8_quant.py

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

tests/kernels/test_layernorm.py

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