OZG-7837 save each aggregations in own collection

src/main/java/de/ozgcloud/aggregation/AggregationLoader.java

...ava/de/ozgcloud/aggregation/AggregationManagerRunner.java

...ava/de/ozgcloud/aggregation/TransformationProperties.java

...gcloud/aggregation/transformation/AggregationMapping.java

...loud/aggregation/warehouse/CustomWarehouseRepository.java

.../aggregation/warehouse/CustomWarehouseRepositoryImpl.java

...java/de/ozgcloud/aggregation/warehouse/DocumentEntry.java

...t/java/de/ozgcloud/aggregation/AggregationLoaderTest.java

...de/ozgcloud/aggregation/AggregationManagerRunnerTest.java

...egation/transformation/AggregationMappingTestFactory.java

...regation/warehouse/CustomWarehouseRepositoryImplTest.java