Refactor updateZaak zaak patch creation to resolve issues with information loss of ZDS value=noValue and absence of element difference

[MLenterman]

value="noValue" during updateZaak means that a the field on a zaak needs to be set specifically to no/empty value. The absence of an element in the input message means that the element should not be changed, but simply keep whatever value is already present for it.

This information is lost when translating ZDS zaak to ZGW zaak. Thats why currently the xslt that creates the zaak patch is using the current ZGW zaak in combination with the "wordt" ZDS zaak.

The goal should be to resolve this information loss somehow during the ZDS to ZGW translation, so that it could be used as a template for all other ZDS to ZGW translations.

[MLenterman]

Should investigate we should use PUT instead of PATCH. There is an issue with the PATCH mechanism for our use case. For example: When we do a POST zaak with vertrouwelijkheidsIndicatie absent in the body, OpenZaak will deduct vertrouwelijkheidsIndicatie from the zaaktype. With PATCH, when we don't pass vertrouwelijkheidsIndicatie, it doesn't do this, because not absent in PATCH means that we are not changing the value that is already there. Only other option is to pass vertrouwelijkheidsIndicatie with null or empty string, but then OpenZaak won't except it, because that value is required to be one of the enum values. I think the PUT operation might behave similarly to POST in this regard and help with resolving this issue.