Add Native Windows Support

[nithin-aashik-mcw]

Summary

Adds native Windows support to DeepSpeed: the CPU-side extension ops (pin_memory, async_io/AIO, and the shared-memory comm backend) now build and run under MSVC, the op_builder/build system and build_win.bat support compiling these ops on Windows, and the unit test harness is runnable on Windows. Also fixes a handful of Windows-specific runtime bugs (paths, timers, MSVC OpenMP loop signedness, header include order) and a few unrelated test flakiness issues found along the way, and adds Windows CI and release wheel-build workflows.

Closes #7276
Closes #7057
Relates to #7744, #7523, #7341

Test plan

• Windows (x64, arm64) CI job (windows-torch-latest.yml) passes
• Unit test suite run on Windows (tests/unit)
• Windows wheel build succeeds via the release workflow

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[nithin-aashik-mcw]

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[nithin-aashik-mcw]

@tohtana @loadams @tjruwase
Could you please take a look at this PR when you get a chance? It adds native Windows support, including x64/ARM64 CI, CPU ops, and Windows wheel builds. I’d appreciate maintainer feedback and review.