[repo] normalize ValidationError on edited entity (closes #2509729)
In CubicWeb, ValidationError.entity MUST be the eid of the involved entity,
not the entity iteself (as done by yams).
debian/tmp/usr/lib/PY_VERSION/site-packages/cubicweb/web usr/lib/PY_VERSION/site-packages/cubicweb
debian/tmp/usr/share/cubicweb/cubes/shared/data usr/share/cubicweb/cubes/shared
debian/tmp/usr/share/cubicweb/cubes/shared/wdoc usr/share/cubicweb/cubes/shared