[llvm] [cmake] Set up llvm-ml as ASM_MASM tool in WinMsvc.cmake (PR #104903)

[Martin Storsjö via llvm-commits]

mstorsjo wrote:

> Somewhat related to this. MSVC provides ml and ml64 to avoid having to pass extra flags. I wonder if we should do something similar with llvm-ml, would make it more of a drop-in replacement.

Yep, that would certainly be nice.

https://github.com/llvm/llvm-project/pull/104903