More reliable DNS assertions for multi-record answers

The DNS checks in Monitoring have been improved.

When a name returns multiple records (e.g. several A/AAAA addresses or nameservers), resolvers used to hand them back in a rotating order (round-robin). This could make assertions on the result fail intermittently – sometimes one IP came first, sometimes another.

What changes:

• Multi-record answers (addresses, nameservers, MX) are now sorted deterministically, so both the display and assertions are reliable across every probe.
• Two new, order-independent assertion operators:
  • equals set (any order) – the answer must consist of exactly the listed values.
  • includes all (any order) – all listed values must be present.
  Enter multiple values comma-separated, e.g. 1.2.3.4, 5.6.7.8.

Recommendation: For names with multiple records, prefer “equals set” or “includes all” over “equals”/“contains”. Existing assertions keep working unchanged – no action required.