Add check if data is available within polygon of user (when datasets are added that are not everywhere in the Netherlands)

[MinkeMulder]

At this point all the datasets that are (going to be) included are datasets with data everywhere in the Netherlands. So every dataset is available for every area the user chooses.
So when in the future datasets are added that are not available everywhere, then there should be a check for selected area of the user which datasets are actually available and these should be shown as options to user.
This also means that in the "dataset_info.csv" there should be a column with geometry or a bounding box per dataset.