Test more types of NAME file

[pp-mo]

As mentioned in @bsherratt review containing this comment : https://github.com/SciTools/iris/pull/4933#discussion_r975181473

We should at least have both NAME II and III version files to test. As a minimu, we can just check that a file loads without errors + matches a CML snapshot, as in the existing load tests.

( ? can't link to review per-se ? )