Delete actors by force should cover affiliations

[KlausIllmayer]

Currently, it is not possible to delete an actor that is an affiliation of other actor(s):

sshoc-marketplace-backend/src/main/java/eu/sshopencloud/marketplace/services/actors/ActorService.java

Lines 123 to 125 in f34b26a

	} else if (actorRepository.existsActorByAffiliationActorId(id)) {
	throw new IllegalArgumentException("Cannot delete actors that are affiliations of other actors!");
	} else {

@tparkola Is there a reason, why we don't delete the affiliations and then the actor if force=true?

This question arose as there is no simple API call to identify which actors are affiliated to an actor. It is therefore not easily possible to identify the actors where the affiliation must be removed so that the affiliation actor in the end can be deleted. Anyway, is this a task that could be done within the delete actor routine if force=true. There are two options to deal with this situation: (1) when deleting an actor with force=true then also delete the affiliations or (2) show somewhere which actors belong to the affiliation actor, e.g. as additional return value of the error message of the mentioned code block.
I prefer option (1).

See for discussion and for examples the issue SSHOC/marketplace-curation#31 - also putting @mkrzmr @laureD19 as watchers.