LMS-2166, LMS-2162 fetch all features of all datasets in one sql

.../openbis/dss/screening/server/DssServiceRpcScreening.java

...bis/plugin/screening/server/logic/PlateDatasetLoader.java

...nbis/plugin/screening/server/logic/WellContentLoader.java

.../plugin/screening/shared/imaging/FeatureVectorLoader.java

...g/shared/imaging/dataaccess/IImagingReadonlyQueryDAO.java

...cisd/openbis/dss/etl/dataaccess/FeatureVectorDAOTest.java

.../cisd/openbis/dss/etl/dataaccess/ImagingQueryDAOTest.java

...bis/dss/etl/dto/api/impl/FeatureDefinitionValuesTest.java

...nbis/dss/etl/featurevector/FeatureVectorUploaderTest.java

...nbis/dss/generic/server/graph/TabularDataHeatmapTest.java

...is/dss/generic/server/graph/TabularDataHistogramTest.java

...r/plugins/ImageAnalysisMergedRowsReportingPluginTest.java

...nbis/dss/screening/server/DssServiceRpcScreeningTest.java

...creening/server/logic/FeatureVectorDatasetLoaderTest.java

...gin/screening/server/logic/HCSImageDatasetLoaderTest.java

...s/plugin/screening/server/logic/ScreeningApiImplTest.java

.../plugin/screening/server/logic/WellContentLoaderTest.java

...gin/screening/shared/imaging/FeatureVectorLoaderTest.java