dname: remove libknot/consts.h include from the header

src/knot/modules/online_sign/nsec_next.c

src/knot/zone/zone-tree.c

src/libknot/dname.h

src/libknot/packet/pkt.h

src/libknot/rrtype/opt.c

src/libknot/rrtype/soa.h

tests/dname.c

tests/modules/online_sign.c