[web/test] Drop folder cube dependency Copy useful schema bits, define IBreadCrumbs adapter for Folder/fild_under (previously relying on ITree adapter) and adjust unittest_viewselector tests to drop a view that does not exist anymore. Related to #5168939.

#!/bin/sh -e
if [ "$1" = "purge" ] ; then
        update-rc.d cubicweb remove >/dev/null
fi
 
#DEBHELPER#
 
exit 0