SP-431 SOB-6: Allow custom image scaling of merged images

...systemsx/cisd/openbis/dss/etl/AbsoluteImageReference.java

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

...dss/generic/server/ImageGenerationDescriptionFactory.java

...openbis/dss/generic/server/images/ImageChannelsUtils.java

...generic/server/images/dto/ImageGenerationDescription.java

.../generic/server/images/dto/ImageTransformationParams.java

.../web/client/application/detailviewers/ChannelChooser.java

...client/application/detailviewers/ChannelChooserPanel.java

.../application/detailviewers/ChannelWidgetWithListener.java

...cation/detailviewers/MaterialReplicaSummaryComponent.java

...ion/detailviewers/UserDefinedRescalingSettingsDialog.java

...b/client/application/detailviewers/WellContentDialog.java

.../web/client/application/detailviewers/WellSearchGrid.java

...tion/detailviewers/dto/LogicalImageChannelsReference.java

...ent/web/client/application/detailviewers/image/Image.java

...lugin/screening/client/web/public/screening-dictionary.js

.../plugin/screening/server/logic/HCSImageDatasetLoader.java

.../openbis/dss/etl/ImageSizeFeedingMaintenanceTaskTest.java

...bis/dss/generic/server/images/ImageChannelsUtilsTest.java

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