Native Windows support

[maleadt]

We currently only support Windows through WSL. Native support involves:

• Level Zero: provided by the closed-source driver, so we just rely on ze_loader.dll
• Libraries: depend on our oneAPI Support library, as Intel vendor libraries only expose a C++ ABI

The problem with building the oneAPI Support library for Windows is that our build environment uses MinGW. This poses issues when linking C++ libraries like sycl7.dll, which exposes a C++ API, and the MinGW and MSVC C++ ABIs are incompatible (see JuliaPackaging/Yggdrasil#8285 (comment)).

AFAIU, there's a couple possible solutions here:

• use clang-cl to target the MSVC ABI from our build environment: this would require significant work on the BinaryBuilder side (or a very hacky build recipe) to ensure the correct SDK/sysroot bits are available
• hope that Intel provides MinGW-compatible binaries
• hope that Intel adds C APIs to its vendor libraries (as the C ABI is compatible between MinGW and MSVC).