Fix EZP-23054: eZIE: Missing form token from Request when closing
(save/quit)

https://jira.ez.no/browse/EZP-23074

Cause of this is that when using a Twig template for the main layout and
doing frontend content editing, CSRF token is not generated as a meta
tag.

This patch ensures there is always a fallback (here with hidden span),
so that one can grab the CSRF token in their JS.