IS_CHAR_DEVICE is path a character device

e.g. NUL, /dev/null false if file does not exist

Windows: Console handles CONIN$, CONOUT$, STDIN, STDOUT, STDERR are not detected. Only NUL is detected. in our C-API-based Ffilesystem library, we use GetFileType() with CreateFile() to detect those handles successfully, but they don't work here.

Ref: https://learn.microsoft.com/en-us/windows/console/console-handles

function ok = is_char_device(file, backend)
arguments
  file {mustBeTextScalar}
  backend (1,:) string = ["python", "sys"]
end

fun = hbackend(backend, "is_char_device");

ok = fun(file);

end