Add a new predicate failure for non-matching withdrawals

[lehins]

Current predicate failure that checks whether withdrawal matches the amount in the reward account is totally misleading. It is reported as WithdrawalsNotInRewardsCERTS, which is also the predicate failure that is used for reporting non-existent reward accounts. We need to create proper predicate failure for that and also fix the name and refactor validateZeroRewards function, cause that is even more misleading.