[web/views] Fix `has_editable_relation` predicate wrt inlined relations Prevents the "modify" action from being shown when there is nothing to edit.

usr/bin/cubicweb-ctl usr/bin/
usr/lib/PY_VERSION/*-packages/cubicweb/cwctl.py
../cubicweb-ctl.bash_completion etc/bash_completion.d/cubicweb-ctl