title: check if given path is a subdirectory of another in golang
body: <p>Say we have two paths:</p>
  
  <p><code>c:\foo\bar\baz</code> and <code>c:\foo\bar</code></p>
  
  <p>Is there any package/method that will help me determine if one is a subdirectory of another? I am looking at a cross-platform option.</p>