libknot: move TTL from rdata to rrset

src/knot/ctl/commands.c

src/knot/dnssec/nsec-chain.c

src/knot/dnssec/nsec-chain.h

src/knot/dnssec/nsec3-chain.c

src/knot/dnssec/policy.c

src/knot/dnssec/rrset-sign.c

src/knot/dnssec/zone-nsec.c

src/knot/dnssec/zone-sign.c

src/knot/events/handlers/load.c

src/knot/journal/serialization.c

src/knot/modules/onlinesign/onlinesign.c

src/knot/modules/synthrecord/synthrecord.c

src/knot/modules/whoami/whoami.c

src/knot/nameserver/chaos.c

src/knot/nameserver/internet.c

src/knot/nameserver/process_query.c

src/knot/updates/apply.c

src/knot/updates/changesets.c

src/knot/updates/ddns.c

src/knot/zone/contents.c