Tracking issue: Peelvenen MetaSWAP-MODFLOW6 test

[JoerivanEngelen]

I sat together with @WouterSwierstra yesterday to convert the Peelvenen iMOD5 model to a coupled MODFLOW6-MetaSWAP-Ribasim model. We ran into some issues, but could work around them and the model ran without error. There were still some issues with the generated MetaSWAP model input though. This issue is to track progress on resolving these issues and the hiccups we ran into.