Fix classes for persons in data and UI

[acka47]

Currently, we display "Individualisierte Person", "Regierender Fürst oder Mitglied eines regierenden Fürstenhauses"/RoyalOrMemberOfARoyalHouse, "Literarische oder Sagengestalt"/LiteraryOrLegendaryCharacter, "Sammelpseudonym"/CollectivePseudonym, "Götter"/Gods, "Geister"/Spirits as different sub-classes of "Person".

In fact, all of them are also of type DifferentiatedPerson/"Individualisierte Person". We should correct this.

Proposed approach

The easiest way which is also consistent with the other super types (e.g. "CorporateBody") would be to remove the type DifferentiatedPerson completely from the data.

Pro arguments for this approach

• There exists no difference between Person and DifferentiatedPerson anymore in GND data as UndifferentiatedPerson as the other type of Person was removed.
• In the UI we would then have Person as top class and below it the existing specified types that would not match up to the number of Persons, just like for the other top classes CorporateBody, ConferenceOrEvent etc.

Contra argument

• If applications rely on the type DifferentiatedPerson they would be broken by this change.

(This issue was reported by Johannes Bracht during a joint meeting of the lobid team (represented by @fsteeg and @acka47) and GND4C project members.)