Use wslpath tool from Windows 10 1803 update

[david50407]

ref: https://blogs.msdn.microsoft.com/commandline/2018/03/07/windows10v1803/

Since 1803 update, Windows 10 provides WSL <> Windows path converter due to new configuration (/etc/wsl.conf) which can set customized Windows mount path (like use /windir/ instead of /mnt/), and this wslpath tool ensures your configuration of path and convert it correctly.