Petascope - Importing with wcst_import gdal general recipe should allow selecting bands

[Dimitar Misev]

The variables format parameter allows to specify the bands or variables to be imported from an input file (​docs)

  // Specify variable names, band ids (0-based), etc.
  "variables": [ "var1", "var2", ... ],

But petascope currently does not support importing a subset of bands (although it does support for grib or netcdf). For example, below is importing 1 band from a png file with 3 bands:

<gml:rangeSet>
    <gml:rangeParameters>
        {"variables": ["1"]}
    </gml:rangeParameters>
    <gml:File>
        <gml:fileReference><![CDATA[
                file:///home/rasdaman/rasdaman_community/rasdaman/systemtest/testcases_services/test_all_wcst_import/testdata/wcs_gdal_select_1band_from_3bands_to_import/rgb.png
            ]]
{{{

}}}
></gml:fileReference>
        <gml:fileStructure>image/png</gml:fileStructure>
    </gml:File>
</gml:rangeSet>

It also needs to fix in wcst_import for gdal general recipe to validate the band identifiers (they must be integer numbers, based 0) which exist in the input multiband files (e.g: rgb.png)

        "slicer": {
          "type": "gdal",
          "bands": [
            {
              "name": "red",
              "identifier": "6" <--- Invalid band idenitifier
            }, {
              "name": "green",
              "identifier": "2"
            }, {
              "name": "blue",
              "identifier": "3" <--- Invalid band identifier
            }
          ],