test_zci: make tests easier to interpret.

- Parallel paths for structured_answers to mirror attributes checking.
- Add '-ANY-' keyword to allow things to match on any result.

Verbose output improvements:
- Wrap each query in a subtest
- Use prefixing to quickly indicate the extent of the test

Perhaps the most controversial thing here is the '-ANY-' keyword, but I
think it's a strong improvement over the fall-back `qr/\.*/` since the
intent is exceptionally obvious and the verbose output will confirm what
is happening.
Quite the writeup @mwmiller! Thanks a lot, my understand of this is much better now.