add get_last_stream to producer

common/cpp/include/common/networking.h

common/cpp/include/database/database.h

common/cpp/include/unittests/MockDatabase.h

common/cpp/src/database/mongodb_client.cpp

common/cpp/src/database/mongodb_client.h

producer/api/cpp/include/producer/producer.h

producer/api/cpp/src/producer_impl.cpp

producer/api/cpp/src/producer_impl.h

producer/api/cpp/unittests/test_producer_impl.cpp

receiver/CMakeLists.txt

receiver/src/request_handler/request_factory.cpp

receiver/src/request_handler/request_factory.h

...er/src/request_handler/request_handler_db_last_stream.cpp

...iver/src/request_handler/request_handler_db_last_stream.h

receiver/unittests/request_handler/test_request_factory.cpp

...s/request_handler/test_request_handler_db_last_stream.cpp

...atic/mongo_db/insert_retrieve/insert_retrieve_mongodb.cpp