resolver: opcode IQUERY must return NOTIMPL

IQUERY was obsoleted by RFC 3425 so we use it to test how resolver responds to unknown opcodes.

sets/resolver/iter_opcode_notimp.rpl

+CONFIG_END
+SCENARIO_BEGIN Test resolver response for unknown opcode
+
+STEP 1 QUERY
+ENTRY_BEGIN
+REPLY IQUERY
+ENTRY_END
+
+STEP 2 CHECK_ANSWER
+ENTRY_BEGIN
+MATCH rcode opcode
+REPLY NOTIMP IQUERY
+ENTRY_END
+
+SCENARIO_END