WinML backend for wasi-nn

[jianjunz]

This change adds Windows Machine Learning backend for wasi-nn. Since WinML is a built-in feature of Windows, this change makes it possible to run wasi-nn on Windows without a third-party machine learning framework.

WinML backend is only available on Windows.

WinML: https://learn.microsoft.com/en-us/windows/ai/windows-ml/

[abrown]

@jianjunz:now that #7846 is merged you should be able to rebase on that and get cargo vet to pass.

[jianjunz]

Thanks for auditing windows-* crates, but cargo vet still fails after #7900. Only 1 unvetted dependency now.

1 unvetted dependencies:
  windows:0.52.0 missing ["safe-to-deploy"]

[jianjunz]

The code is rebased. No conflict. However, cargo vet reported more unvetted dependencies. I'll check if there is any unnecessary change for cargo.lock.

[jianjunz]

Thanks for your review and merging this PR.