refactor broker

broker/src/asapo_broker/database/database.go

broker/src/asapo_broker/database/mock_database.go

broker/src/asapo_broker/database/mongodb.go

broker/src/asapo_broker/database/mongodb_test.go

broker/src/asapo_broker/server/get_commands_test.go

broker/src/asapo_broker/server/get_next.go

broker/src/asapo_broker/server/post_op_image_test.go

broker/src/asapo_broker/server/post_query_images_test.go

broker/src/asapo_broker/server/post_reset_counter_test.go

broker/src/asapo_broker/server/process_request.go

broker/src/asapo_broker/server/process_request_test.go

broker/src/asapo_broker/server/request_common.go

examples/consumer/getnext_broker/getnext_broker.cpp

tests/automatic/consumer/consumer_api/consumer_api.cpp

tests/manual/performance_broker_receiver/getlast_broker.cpp