zone: run disabled validation cases

[aberoham]

Three test cases were disabled with it.skip because the validation they check was commented out. Running them meant deciding what the schemas should do.

zone applies .domain() again. Before this, a zone name was any string of 3 to 255 characters.

The commented-out rule on zone_record.owner went the other way. An owner is the left-hand name of a resource record, either relative to its zone (www) or fully qualified (www.example.com.). The rule was .hostname({ allowFullyQualified: false }), and it rejects 128 of the 143 distinct owner values in a populated database:

* , *.something , some.*.thing , 0 , 1 , 10 , 1.2.0.192.in-addr.arpa.

Wildcards, bare numeric labels in a reverse zone, and qualified owners are all ordinary. So owner gets a grammar built from what DNS allows. RFC 1035 labels, widened by the underscore labels of RFC 8552. The asterisk that RFC 4592 makes a wildcard in the leftmost label and a literal anywhere else. Labels cap at 63 characters and the name at 255.

Measured against the same database it accepts all 143. It still rejects a..b, a b, a/b, .leading, and an over-long label.

validate:  306 tests, 305 pass, 1 skipped
api:       mysql 404/404, json 381/381

The skip is the RR-fields check. It needs the dns-resource-record checkout beside this one.