Added storing of quadkey and geometry of OBM buildings to the gde_buildings table of the GDE Tiles database.
The quadkey allows to later search (to export with gde-exporter, for example) for the buildings associated with a particular tile.
The geometry is useful because the gde_buildings table of the GDE Tiles database is different from the obm_buildings table of the OBM Buildings database, because rabotnik-obm does not gather parts of buildings that are defined by a relation. The gde-core code compensates for that and carries out this collection. This means that retrieving the geometries from either obm_buildings or the OSM Replication database adds unnecessary complexity. In the future, the bringing together of parts of relations should be done by rabotnik-obm.
Tests have been adapted accordingly.
I've carried out a test run locally using a Greek admin unit and it worked well.