[WindowsDriver] Always consider `WinSdkVersion` (#130377)
Currently, the `-Xmicrosoft-windows-sdk-version` is only used if
`-Xmicrosoft-windows-sdk-root` is also provided. This is a surprising
behavior since the argument should still be taking effect if LLVM uses
the Windows SDK root from the registry.
Tested locally in a simple Hello World program including `Windows.h` and
compiled with `-Xmicrosoft-windows-sdk-version 10.0.18362.0` on a system
where the SDK 10.0.22621.0 is also installed and verified that the
correct header was included.
Co-authored-by: Saleem Abdulrasool <compnerd@compnerd.org>
