migrate every factory query off BuildingSystem onto the free functions

src/lib/sim/FactoryQueries.h

@@ -39,6 +39,9 @@ int getActiveProductionBuildingCount(const FactoryState& state);
 
 bool isTileOccupied(const FactoryState& state, QPoint tile);
 
+// True while the building is in the deconstruction queue (REQ-BLD-DECON-QUEUE).
+bool isQueuedForDeconstruction(const FactoryState& state, BuildingId id);
+
 // The nearest building of the given type to a world position, or nullptr when
 // none exists. Distance is measured to the building's footprint centre.
 const Building* findNearestBuilding(const FactoryState& state, QVector2D worldPos,