refactor, implement last_ack_id

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_id_test.go

broker/src/asapo_broker/server/get_last_test.go

broker/src/asapo_broker/server/get_lastack.go

broker/src/asapo_broker/server/get_meta_test.go

broker/src/asapo_broker/server/get_nacks_test.go

broker/src/asapo_broker/server/get_next_test.go

broker/src/asapo_broker/server/get_size_test.go

broker/src/asapo_broker/server/get_substreams_test.go

broker/src/asapo_broker/server/listroutes.go

consumer/api/cpp/include/consumer/data_broker.h

consumer/api/cpp/src/server_data_broker.cpp

consumer/api/cpp/src/server_data_broker.h

consumer/api/cpp/unittests/test_server_broker.cpp