[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.

version=3
opts=uversionmangle=s/(rc|a|b|c)/~$1/ \
http://pypi.debian.net/cubicweb/cubicweb-(.+)\.(?:zip|tgz|tbz|txz|(?:tar\.(?:gz|bz2|xz)))