Order of attributes in collection.yaml

This is especially related to 'Rights Holder' & 'Collector'...as they are currently completely separated.

So it would be good to have them at the top and next to each other.

A possible order could look like this:

collection:
    title:
    rights_holder:
    collector:
    basic_classifications:
    gnd_subjects:
    attributes:
        mandatory:
            ...
        optional:
            ...
    elements: []