title: how to addcommenter to one file without sending email
body: <p>We have students' attendances files shared with their families (commenter permission only).</p>
  
  <p>It seems that some of the sharings weren't correctly done in the first time, when the script created the files.</p>
  
  <p>So I want to do a bulk re-sharing with them, <strong>but not sending any email</strong>. They are more than than 500 families, and I don't want to disturb or confuse them with a message.</p>
  
  <p>file.addCommenter seems to send an automatic email.</p>
  
  <p>is it possible not to send it?</p>
  
  <p>Thanks,</p>
  
  <p>Enrique</p>