rasql - wrong struct type for band subsetting import by gdal driver

[Bang Pham Huu]

This ticket is needed for #2130

Run these rasql commands to reproduce with importing only 1 the first band from 3 bands RGB file:

rasql -q 'CREATE TYPE test_wcs_gdal_select_1band_from_3bands_to_import1_Array AS char MDARRAY [D0,D1]' --user rasadmin --passwd rasadmin
rasql -q 'CREATE TYPE test_wcs_gdal_select_1band_from_3bands_to_import1_Set AS SET (test_wcs_gdal_select_1band_from_3bands_to_import1_Array NULL VALUES [119.0])' --user rasadmin --passwd rasadmin
rasql -q 'CREATE COLLECTION test_wcs_gdal_select_1band_from_3bands_to_import1 test_wcs_gdal_select_1band_from_3bands_to_import1_Set' --user rasadmin --passwd rasadmin

rasql -q 'INSERT INTO test_wcs_gdal_select_1band_from_3bands_to_import1 VALUES <[0:0,0:0] 119c> TILING ALIGNED [0:1023, 0:1023] TILE SIZE 4194304' --user rasadmin --passwd rasadmin
rasql -q 'UPDATE test_wcs_gdal_select_1band_from_3bands_to_import1 SET test_wcs_gdal_select_1band_from_3bands_to_import1[0:399,0:343] ASSIGN decode(<[0:0] 1c>, "GDAL", "{\"variables\":[0],\"filePaths\":[\"YOUR_RASDAMAN_SOURCE_PATH/systemtest/testcases_services/test_all_wcst_import/testdata/wcps_rgb/rgb.png\"]}")'

Then, it has this error

2019-08-05 14:37:41,147, qlparser/qtupdate.cc:192: Base type of source object (struct { char , char  }) 
does not match the base type of the target object (char)