start refactor connection

receiver/CMakeLists.txt

receiver/src/connection.cpp

receiver/src/connection.h

receiver/src/request.cpp

receiver/src/request.h

receiver/src/requests_dispatcher.cpp

receiver/src/requests_dispatcher.h

receiver/unittests/test_connection.cpp

receiver/unittests/test_request.cpp

receiver/unittests/test_requests_dispatcher.cpp