Improve PDS REST API documentation by RestDoc tests

[de-jcup]

Situation

https://daimler.github.io/sechub/latest/sechub-product-delegation-server.html#rest-api Does not contain correct RESTDoc test outputs, but static content - which is not enough

Wanted

For the PDS restcontrollers we create dedicated PDS{restControllerName}DocTest.java pendants - like in SecHub itself. The generated output must be available inside PDS documentation.

[de-jcup]

It must be discussed, if we really need the documentation. PDS is just used internally by SecHub and so currently not a public API which must be documented.

So at least, this is somehting which can be done later.