Fix portable library build on Windows

[GregoryComer]

Enable build of the portable operator library (and executor_runner, now that we have portable) on the Windows preset. There are a couple of patterns that weren't building on Windows. Both std::nan and std::signbit complain about ambiguous overload resolution when given an integer argument.

To solve the std::isnan issue, I introduced isnan_override in math_util.h, following the naming pattern from max_override / min_override / etc. in the same file. It adds a specialized branch for integers to avoid calling std::isnan. For std::signbit, I just locally specialized.

[GregoryComer]

Stack from ghstack (oldest at bottom):

• -> Fix portable library build on Windows #13260
• Fix XNNPACK build on Windows #13259
• Create Windows CMake preset #13257
• Fix devtools CMake build failure on Windows #13251
• Fix error reporting in Windows preset build job #13247
• Always run build-presets workflow on PRs/pushes #13243

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/13260

• 📄 Preview Python docs built from this PR

Note: Links to docs will display an error until the docs builds have been completed.

❌ 5 New Failures, 1 Unrelated Failure

As of commit 6e6ab75 with merge base 4ce7078 ():

NEW FAILURES - The following jobs have failed:

• Build documentation / build (buck2) / Build doc (gh)
  At least one of the pre-conditions you specified did not hold
• Build Presets / windows (pybind) / build (gh)
  Process completed with exit code 1.
• Build Presets / windows (windows) / build (gh)
  Process completed with exit code 1.
• pull / test-llava-runner-linux / linux-job (gh)
  RuntimeError: Command docker exec -t 49512f03d8f35e9ae21a07a3d2c76e1c7f7a202d0cb1c16b0f7e708ea92ab751 /exec failed with exit code 139
• pull / test-moshi-linux / linux-job (gh)
  RuntimeError: Command docker exec -t ffa6f7d657303f75eebcdbb80105779c7c0fd5c5f98c3b4006ee2b2156f8c413 /exec failed with exit code 1

BROKEN TRUNK - The following job failed but were present on the merge base:

👉 Rebase onto the `viable/strict` branch to avoid these failures

• pull / test-openvino-linux / linux-job (gh) (trunk failure)
  AttributeError: '_OpNamespace' 'quantized_decomposed' object has no attribute 'convert_element_type'

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[GregoryComer]

@manuelcandales Any thoughts or preference on the approach used here?