[autoform] Avoid two calls to field.process_form for the same field in some cases when some entity is being created and data include non-inlined relations, the values for this relation are now stored for later usage, avoiding two calls to field's process_form method, which may be unexpected for custom fields. This has been discovered in saem_ref#f5444b1f9770. Reorganize imports in the test along the way.

#!/bin/sh -e

if [ "$1" = "purge" ] ; then
        rm -rf /etc/cubicweb.d/
        rm -rf /var/log/cubicweb/
        rm -rf /var/lib/cubicweb/
fi

#DEBHELPER#
 
exit 0