migrate every factory query off BuildingSystem onto the free functions

src/lib/sim/FactoryQueries.cpp

@@ -77,6 +77,12 @@ bool isTileOccupied(const FactoryState& state, QPoint tile)
     return state.grid.isOccupied(tile);
 }
 
+bool isQueuedForDeconstruction(const FactoryState& state, BuildingId id)
+{
+    const Building* building = findBuilding(state, id);
+    return building && building->queuedForDeconstruction;
+}
+
 const Building* findNearestBuilding(const FactoryState& state, QVector2D worldPos,
                                     BuildingType type)
 {