client download functionality regression

• broken for emergency and any newly registered collection
• we used to rewrite productid to productid__coverage to get coverageid but now naming of coverage identifiers changed to be in format productid__rasteridentifier__coverage which is shown correctly in WCS links in summary, but download panel can not use those yet - need to be implemented in eoxc. During implementation, take in account, that more coverages can now be available for one product (pan/ms). or multiband 1 band = 1 coverage for S2L2A - for example here https://vs-s52gfrubv875jlgrfdsa.demo.hub.eox.at/opensearch/collections/S2L2A/atom/?bbox=-8.302734375,38.859619140625,32.302734375,59.140380859375&start=2020-08-01T00:00:00.000Z&end=2020-08-31T23:59:59.000Z

 <owc:operation code="GetCoverage" method="GET" type="image/tiff" href="https://vs-s52gfrubv875jlgrfdsa.demo.hub.eox.at/ows?service=WCS&amp;version=2.0.1&amp;request=GetCoverage&amp;coverageId=S2A_33UWP_20200816_0_L2A_B02"/>
<owc:operation code="DescribeCoverage" method="GET" type="application/xml" href="https://vs-s52gfrubv875jlgrfdsa.demo.hub.eox.at/ows?service=WCS&amp;version=2.0.1&amp;request=DescribeCoverage&amp;coverageId=S2A_33UWP_20200816_0_L2A_B03"/>

• also breaks in EOEPCA