utils: add support for quering all resolved addresses and improve kdig processing

Getaddrinfo result for remote server is stored in net_t structure. This allows
to query each resolved address via net_t.srv. It is important for example if
the server has associated AAAA and A records, but listens on IPv4 address only.

refs #2137

Change-Id: Iadd2b011a25a8d9e13f05b239a78f42f8d69b5de