[sql gen] Explicitly name unique index This patch hotfix logilab database for https://www.logilab.org/6662663 and fix database creation to stop using UNIQUE in the table schema but rather create the index later on, so its name is under control. Also consider this change in schema synchronization hooks. This is preliminary work related to #13822045

missing-dep-for-interpreter make => make | build-essential | dpkg-dev (usr/*/cubicweb/skeleton/debian/rules.tmpl)