Feature request: Show time of deletion (deletion_timestamp) for mails in powermail Backend module

[sypets]

For existing Powermail Mails show the deletion time in the BE module

e.g.

Should probably be added in powermail:

Resources/Templates/Partials/Module/List.html

<f:if condition="{mail.deletionTimestamp}">
  <dl class="powermail_listbe_details_dl powermail_listbe_details_dl_additional">
      <dt>
        <strong><f:translate key="...</strong>
   </dt>
   <dd>
     <f:format.date format="d.m.Y" >{mail.deletionTimestamp}</f:format.date>
   </dd>
  </dl>
</f:if>