message: fix: mark mam messages as read
  regression introduced after 4.0
diff: @@ -139,6 +139,7 @@ export default class Archive {
  htmlMessage: htmlBody.html(),
  stamp: stamp.getTime(),
  mark: MessageMark.transferred,
  + unread: false,
  sender: undefined,
  };
  @@ -188,6 +189,7 @@ export default class Archive {
  direction: Message.DIRECTION.SYS,
  plaintextMessage: Translation.t('Archive_exhausted'),
  mark: MessageMark.transferred,
  + unread: false,
  });
  transcript.unshiftMessage(archiveExhaustedMessage);
  