Support building with win-clang #19630

Chrome and V8 support building with Clang on windows. Node.js should include support for this too.

Benefits:

• Future proof. Chrome is already deprecating MSVC build. V8 might do the same in the long-term.
• No more dependency on installing Visual Studio. Clang is open source.

Blockers:

• Expose clang build in configure.
• Official way to build V8 on Windows is to use ninja. However, gyp backend for ninja only supports MSVC.
• openssl.gyp requires llvm_version to be set.
• Actually fetching Clang. This is done in V8 through python .\deps\v8\tools\clang\scripts\update.py.
• Version and macro detection does not work with clang-cl.exe.