@Override
        public String toString() {
            return itemGroups.stream()
                    .map(Objects::toString)
                    .collect(Collectors.joining("\n"));
        }
Create a {@link ProxyZipSnapshot} of the supplied zip file path.
This assumes the zip is a proxy zip containing entries with extensions .dat/.meta/.mf/.ctx
stroom-proxy/stroom-proxy-app/src/test/java/stroom/proxy/app/handler/TestDataUtil.java