SSDM-4003: New DSS FS (FTP / CIFS) resolvers: fix NPEs, change log levels

...stemsx/cisd/openbis/dss/generic/server/cifs/CifsFile.java

...isd/openbis/dss/generic/server/cifs/CifsServerLogger.java

...cisd/openbis/dss/generic/server/cifs/DataSetCifsView.java

.../dss/generic/server/ftp/v3/V3ExperimentLevelResolver.java

.../dss/generic/server/ftp/v3/V3FtpPathResolverRegistry.java

.../generic/server/ftp/v3/V3HierarchicalContentResolver.java

...bis/dss/generic/server/ftp/v3/V3ProjectLevelResolver.java

...enbis/dss/generic/server/ftp/v3/V3SpaceLevelResolver.java

.../generic/server/ftp/v3/plugins/V3DataSetTypeResolver.java