first cut at change-data-outside-ichabod cuke

@barnabyalter @NYULibraries/hydra I've taken a first cut at the "change data outside ichabod" tests for user story 70857552. Would be great to get some feedback on this.

Not sure if it's good practice to change Ichabod data from within a cucumber "given" step, but I can't think of any other way to test this scenario. VCR cassettes recorded the transactions properly, and the tests pass.
@barnabyalter @NYULibraries/hydra Also, FYI, I tweaked this helper to make it slightly more generalizable. Previously, it assumed that there would only be one dd following sibling, and it passed because "Additional Information" was the last field displayed. Now it explicitly selects & verifies the content of the _next_ dd following sibling. I think this is better.