[Receiver] Added Unittests for FabricNetServer

common/cpp/include/common/networking.h

common/cpp/include/unittests/MockFabric.h

common/cpp/include/unittests/MockIO.h

common/cpp/src/http_client/curl_http_client.cpp

consumer/api/cpp/unittests/test_server_broker.cpp

receiver/CMakeLists.txt

...rc/receiver_data_server/net_server/fabric_rds_request.cpp

.../src/receiver_data_server/net_server/fabric_rds_request.h

...src/receiver_data_server/net_server/rds_fabric_server.cpp

...r/src/receiver_data_server/net_server/rds_fabric_server.h

...src/receiver_data_server/receiver_data_server_request.cpp

...eceiver_data_server/net_server/test_rds_fabric_server.cpp

...ttests/request_handler/test_request_handler_db_writer.cpp

...ient/curl_http_client_command/curl_httpclient_command.cpp