externalize test data

[raganhan]

We have more implementations of the path extractor, externalizing the test data is a good idea to get some parity between them

[raganhan]

Things to figure out:

• Is the current format good enough?
• where to put it, ion-tests or a new pkg?
• is Just a file skip list fine or should we get more fancy, e.g. skip line, names?