misc cleanup and refactor

.gitlab-ci.yml

src/cmdu_ackq.c

src/config.c

src/host.c

src/host.h

src/host_config.c

src/host_config.h

src/host_nodes.c

src/host_nodes.h

src/host_utils.c

src/host_utils.h

src/json_utils.c

src/mdns_avahi.c

src/nodes.c

src/topo_ieee1905.c

src/topo_ieee1905.h

src/topologyd.c

src/topologyd.h