Add tabindex="-1" via Javascript, in Plone 6

[MrTango]

Since the hidden formfield is not a real field, it should have tabindex="-1" set.
But to make it not to easy for the spammers to find it, it should be set via Javascript.
We could do this directly in the template we have, but for Plone 5 the following would fail because of requirejs:

<script type="text/javascript">
  document.querySelector("#formfield-form-widgets-${view/honeypot_field_name}")[0].setAttribute("tabindex", "-1");
</script>

i suggest to only add this for the next major which should be Plone >= 6.