add Error class

common/cpp/include/common/error.h

common/cpp/include/database/database.h

common/cpp/include/system_wrappers/io.h

common/cpp/include/system_wrappers/system_io.h

common/cpp/include/unittests/MockIO.h

common/cpp/src/database/database.cpp

common/cpp/src/database/mongodb_client.cpp

common/cpp/src/database/mongodb_client.h

common/cpp/src/system_io/system_io.cpp

common/cpp/src/system_io/system_io_linux.cpp

common/cpp/src/system_io/system_io_windows.cpp

examples/worker/getnext_broker/getnext_broker.cpp

examples/worker/process_folder/process_folder.cpp

tests/common/cpp/src/testing.cpp

tests/mongo_db/connect/CMakeLists.txt

tests/mongo_db/connect/connect_mongodb.cpp

tests/mongo_db/insert/CMakeLists.txt

tests/mongo_db/insert/insert_mongodb.cpp

tests/system_io/read_file_content/CMakeLists.txt

tests/system_io/read_file_content/read_file_content.cpp