added integration test for datasets

common/cpp/src/database/mongodb_client.cpp

examples/worker/getnext_broker/getnext_broker.cpp

tests/automatic/full_chain/CMakeLists.txt

.../automatic/full_chain/simple_chain_dataset/CMakeLists.txt

.../automatic/full_chain/simple_chain_dataset/check_linux.sh

...tomatic/full_chain/simple_chain_dataset/check_windows.bat

worker/api/cpp/include/worker/data_broker.h

worker/api/cpp/src/folder_data_broker.cpp

worker/api/cpp/src/folder_data_broker.h

worker/api/cpp/src/server_data_broker.cpp

worker/api/cpp/src/server_data_broker.h

worker/api/cpp/unittests/test_server_broker.cpp