Reference tests for ADVZ structs (and others?)

[ggutoski]

A reference test ensures that new code changes do not break backwards compatibility for serialization of certain data structs. We should add such tests to jf-vid package, and probably others, too, such as jf-pcs. These tests should follow the example from the espresso-sequencer repo: https://github.com/EspressoSystems/espresso-sequencer/blob/1587f4ae0d485e69c2547831e669e2087aab82bf/data/README.md