[SDKs] Teach arv-copy to copy whole projects
Currently, trying to copy a project aborts with the error:
arv-copy: cannot copy object UUID of type Group
It would be nice to be able to copy entire projects wholesale, to have all of their contents on a different cluster.
UI issue to settle: this has the same problem rsync does: should this operation create a new subproject in the destination project? Or should it copy all of the source project's contents into the destination project directly? I think we should follow the principle of least surprise here, but I think that's mostly an architect question.