SSDM-4197 : Refactoring

...er/dss/plugins/harvester/config/BasicAuthCredentials.java

...neric/server/dss/plugins/harvester/config/SyncConfig.java

...plugins/harvester/config/SynchronizationConfigReader.java

...rver/dss/plugins/harvester/synchronizer/DSSFileUtils.java

...ter/synchronizer/DataSetRegistrationIngestionService.java

...s/plugins/harvester/synchronizer/DataSourceConnector.java

...ss/plugins/harvester/synchronizer/EntitySynchronizer.java