GH-49437: [Python][GPU] Support legacy and native Numba CUDA context handles

[contentis]

Closes #49437

Numba-CUDA 0.28 changed CUDA context handles from ctypes.c_void_p to native cuda.bindings.driver.CUcontext objects. PyArrow currently expects incoming handles to have .value and also always returns ctypes.c_void_p when converting back to Numba.

I added a small compatibility layer which:

• Accepts both legacy ctypes handles and native CUcontext objects.
• Returns the representation expected by the installed Numba implementation.
• Explicitly tests both representations instead of assuming .value.
• Removes CUDA 11 from the Python CUDA jobs while keeping the existing C++ CUDA 11 coverage.
• Numba and cuda.bindings are intentionally imported lazily here since they are optional dependencies. Not sure how happy I am with this bit but it was the best solution in my opinion.

There is also a temporary numpy<2.5 constraint for the Numba-CUDA environment. Numba-CUDA 0.30.4 currently uses the removed np.row_stack attribute with NumPy 2.5. This is already being handled upstream in NVIDIA/numba-cuda#916 and the constraint can be removed once that fix is released.

Testing

I tested the full CUDA Numba interop suite locally with:

• Numba-CUDA 0.27: 50 passed
• Numba-CUDA 0.28: 50 passed
• Numba-CUDA 0.30.4: 50 passed

Cython compilation, linting and ShellCheck also pass.

• GitHub Issue: [Python][C++][GPU] Python Cuda jobs fail with 'cuda.bindings.driver.CUcontext' object has no attribute 'value' #49437

[github-actions]

⚠️ GitHub issue #49437 has been automatically assigned in GitHub to PR creator.