ModelPersistence: drop BinarySModel, replace with DefaultSModel - no reason for SModelData to care about persistence.
ModelPersistence: drop BinaryModelHeader, replace with SModelHeader - no reason to duplicate lazily loaded header.
ModelPersistence: drop BinarySModelDescriptor, replace with DefaultSModelDescriptor - no reason to duplicate lazy implementations of openapi.SModel when their persistence difference is encapsulated within LazyModelFacility. PersistenceVersionAware models can tell actual factory in use to help those interested in actual persistence (although it's bad idea to rely on specific model persistence, and hardly justifiable even for our internal optimization code)