This adds tests to the statschannel system test for testing if
the dnskey sign operation counters are incremented correctly.
It tests three cases:
1. A zone maintenance event where all the signatures that are about
to expire are resigned.
2. A dynamic update event where the new RR and other relevant records
(SOA, NSEC) are resigned.
3. Adding a standby key, that means the DNSKEY and SOA RRset are
resigned.
