Introduced StochasticSoilModelCollection which is an ObservableList of StochasticSoilModel with an added property for the last known file path. Set last known file path from the importer when import is successful. Renamed PipingSoilProfilesImporter to StochasticSoilModelImporter to better match its responsibility. Used string interpolation and nameof. Inlined resources in tests. Related to Issue [WTI-1080]