socket_monitor: extract socket monitoring from etcp_connections, add per-instance context

- New files: transport_layer/socket_monitor.c/h — socket state monitoring with per-instance ctx
- etcp_api: expose get_latency/1s_pkt_count measuring, add etcp_hashrnd for tests
- utun_instance: store socket_monitor per instance, add is_socket_ok check
- topo_node: detect IPv4 addresses with port from listening sockets
- topo_group: use node_name for display in routes
- Makefile.am: add socket_monitor.c to build

src/routing_layer/topo_node.h

@@ -181,6 +181,8 @@ int topo_node_deserialize(struct TOPO_GROUP* group, const uint8_t* data, size_t
                           uint16_t* out_cumulative_rtt);
 
 int topo_group_update_my_nodeinfo(struct UTUN_INSTANCE* instance, struct TOPO_GROUP* group);
+void topo_node_update_my_addresses(struct UTUN_INSTANCE* instance);
+void topo_node_on_socket_changed(struct ETCP_SOCKET* sock, int event, void* arg);
 void topo_node_dump_all(struct TOPO_GROUP* group);
 int  topo_node_format_all(struct TOPO_GROUP* group, char* buf, size_t buf_size);
 int  topo_node_ping_request_cbk(struct TOPO_GROUPS* groups, uint64_t node_id);