[schema] drop CWSourceSchemaConfig[cw_for_source,cw_schema] unique constraint (closes #1946277)
as they are not necessarily unique, eg when one want a configuration for both
subject and object
debian/tmp/usr/lib/PY_VERSION/site-packages/cubicweb/common/ usr/lib/PY_VERSION/site-packages/cubicweb
debian/tmp/usr/lib/PY_VERSION/site-packages/cubicweb/entities/ usr/lib/PY_VERSION/site-packages/cubicweb
debian/tmp/usr/lib/PY_VERSION/site-packages/cubicweb/ext/ usr/lib/PY_VERSION/site-packages/cubicweb
debian/tmp/usr/share/cubicweb/cubes/ usr/share/cubicweb/
debian/tmp/usr/lib/PY_VERSION/site-packages/cubicweb/*.py usr/share/pyshared/cubicweb