(#5479) Test that we auto-require the zone dataset.

This adds a test at the catalog level to ensure that we generate the right
graph relationships; this indirectly tests that the underlying code does the
right thing, but importantly also makes us fairly immune to low level changes.

Reviewed-By: Daniel Pittman <daniel@puppetlabs.com>
Reviewed-By: Matt Robinson <matt@puppetlabs.com>