canonical does not support device UNC path

[forworldm]

Describe the bug
canonical("//./UNC/localhost/c$/foo") throws exception

To Reproduce
See above

Expected behavior
MSVC STL gives \\localhost\c$\foo

Additional context
OS Windows

maybe use GetFinalPathNameByHandleW

[gulrak]

I'll look into that. As I'm at a conference in a few days, it might take me until after it to fix it, at least there can not be a release before I'm back.