Add support for a denormalized version of the provenance DB

in db schema, relation tables (xxx_in_yyy) are denormalized, meaning the
yyy relation (and the location, if any) are stored as arrays.

Denormalized schema is chosen at db creation time using one of the 2
"-denormalized" flavors (aka "with-path-denormalized" or
"without-path-denormalized").