Add tests using PRIVATEOID algorithms

Add tests using PRIVATEOID algorithms

There are 4 tests:

1) a zone using a known private OID.  Validations should succeed
and return AD=1.

2) a zone using an unknown private OID.  Validation should succeed
and return AD=0 as the DS to DNSKEY has provably unsupported
algorithm.

3) a zone using a known private OID and an extra DS record. Validation
should succeed as there is DS to DNSKEY with a known algorithm
linkage.

4) a zone using an unknown private OID and an extra DS record.
Validation should fail as only one of the DS records can be matched
to a provable unknown algorithm.  The algorithm of the second DS
is indeterminate.