Merge #2228

2228: Fix broken q-s-m tests and all bugs that appeared r=mrBliss a=mrBliss

In #1739, I made some changes as some of our q-s-m infrastructure had been adopted by quickcheck-state-machines. Unfortunately, because of confusion with different types adopted in quickcheck-state-machines than the ones we use, our postconditions started checking the result of the implementation with the result of the *implementation* instead of the result of the model 🤦.

Revert the changes that led to this and fix all bugs there were hidden because of it.


Co-authored-by: Thomas Winant <[email protected]>