LMS-2225 save colors for channels in the db

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

...sx/cisd/openbis/dss/etl/ImagingDatabaseVersionHolder.java

...msx/cisd/openbis/dss/etl/dataaccess/IImagingQueryDAO.java

.../ch/systemsx/cisd/openbis/dss/etl/dto/api/v1/Channel.java

...ystemsx/cisd/openbis/dss/etl/dto/api/v1/ChannelColor.java

...isd/openbis/dss/etl/dto/api/v1/SimpleImageDataConfig.java

...openbis/dss/etl/jython/SimpleImageDataSetRegistrator.java

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

...enbis/plugin/screening/shared/basic/dto/ImageChannel.java

.../plugin/screening/shared/basic/dto/ImageChannelColor.java

...in/screening/shared/basic/dto/ImageDatasetParameters.java

...bis/plugin/screening/shared/imaging/HCSDatasetLoader.java

...in/screening/shared/imaging/dataaccess/ImgChannelDTO.java

screening/source/sql/postgresql/012/data.sql

screening/source/sql/postgresql/012/schema-012.sql

...ng/source/sql/postgresql/012/upload-screening-metadata.sh

...ing/source/sql/postgresql/migration/migration-011-012.sql

...msx/cisd/openbis/dss/etl/dataaccess/ChannelColorTest.java

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

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