Implement replay checker

[sebastianburckhardt]

Implements a replay checker which runs in all tests.

The replay checker maintains a serialized checkpoint of the current state, and validates the commutative diagram after each step: serialize(apply-effect(deserialize(old state))) = serialize(new state)

To implement this, some refactoring was also required:

• Generalizes test hook structure to allow for various test checkers to be added easily and independently
• Further develops the EffectTracker abstraction, using an abstract class instead of anonymous functions as done previously.