[facets] support for `no_relation` on RelationFacet e.g. to filter en entities *without* a given relation as well as with a particular relation. Proposed or not by default according to relation cardinality. Also, try to guess i18nable properly from the schema by default.

cubicweb-web: embedded-javascript-library usr/share/cubicweb/cubes/shared/data/jquery.js