Add a single contact/Person model to which all other models associate, if needed

[coeit]

Currently BrAPI has different schemas and attribute combinations to associate a record to a related contact or person. Sometimes its a link to a specific contact, sometimes leadPerson and sometimes a Person. This could be simplified by adding a model, which covers all those cases in a single schema. Attributes should be a combination of the attributes in existing BrAPI schemas:

https://app.swaggerhub.com/apis/PlantBreedingAPI/BrAPI-Core/2.0#/Person
https://app.swaggerhub.com/apis/PlantBreedingAPI/BrAPI-Core/2.0#/Contact