logname: Support Windows

[oech3]

Maybe, easy to do that.

[ChrisDenton]

This should simply involve calling GetUserNameW instead of libc::getlogin.

[oech3]

Already used by whoami. Does it do different things with whoami? https://github.com/uutils/coreutils/blob/main/src/uu/whoami/src/platform/windows.rs

[ChrisDenton]

Hm, it could try using WTSQuerySessionInformationW to get the actual remote desktop session even if the process is run as a different user.