some refactoring

CMakeModules/FindRdKafka.cmake

common/cpp/include/asapo/kafka_client/kafka_config.h

common/cpp/src/kafka_client/rdkafka_client.cpp

common/cpp/src/kafka_client/rdkafka_client.h

receiver/src/main.cpp

receiver/src/receiver_config.cpp

receiver/src/request_handler/request_factory.cpp

...iver/src/request_handler/request_handler_kafka_notify.cpp

receiver/unittests/mock_receiver_config.cpp

receiver/unittests/request_handler/test_request_factory.cpp

receiver/unittests/test_config.cpp

...r_receiver/transfer_single_file_with_kafka/CMakeLists.txt