Vector data importer: Import Cross-section data

[leendertvanwolfswinkel]

This is a slightly different than the other importers, in the sense that there is not a single target layer. The idea is that the user has a schematisation that already contains Pipes, Culverts, Orifices, Weirs, and/or Cross-section locations, but (some of) these objects do not yet have cross-section data or their cross-section data needs to be updated. They have an external dataset that contains the cross-section data.

Further details of how this should work is described in the spreadsheet, in the tab "Cross-section data" https://nelenschuurmans-my.sharepoint.com/%E2%9D%8C/g/personal/leendert_vanwolfswinkel_nelen-schuurmans_nl/ETjOz94ZsbJOsKk18jfZZNMBWUkhxw3oVDim7wc9MlDydw?e=CndJSn