added OpenFile and tests

CMakeModules/testing_cpp.cmake

common/cpp/include/common/file_info.h

common/cpp/include/system_wrappers/io.h

common/cpp/include/system_wrappers/system_io.h

common/cpp/src/system_io.cpp

common/cpp/src/system_io_linux.cpp

tests/system_io/read_folder_content.cpp

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

worker/api/cpp/src/data_broker.cpp

worker/api/cpp/src/folder_data_broker.cpp

worker/api/cpp/src/folder_data_broker.h

worker/api/cpp/unittests/test_folder_broker.cpp

worker/api/cpp/unittests/test_worker_api.cpp