title: Rails + ActiveStorage on S3: Set filename on download?
body: <p>Is there a way to change/set the filename on download?</p>
  
  <p>Example: Jon Smith uploaded his headshot, and the filename is <code>4321431-small.jpg</code>. On download, I'd like to rename the file to <code>jon_smith__headshot.jpg</code>.</p>
  
  <p>View:
  <code>&lt;%= url_for user.headshot_file %&gt;</code> </p>
  
  <p>This <code>url_for</code> downloads the file from Amazon S3, but with the original filename. </p>
  
  <p>What are my options here?</p>