Fix an inconsistency in `GOV` rule:
* Verification of `PrevGovActionId` in `proposalsAddAction` happens on accumulated `proposals` * While `preceedingHardFork` check happens on original `st`. In a usual application, which has identifiers assigned, this inconsistency would be a problem. However, in a transaction`GovActionId` is derived from a hash of a transaction itself. This means that it is impossible to reference a previous governance action within the same transaction, since you'd need to know a hash of a transaction that contains the proposal itself. Therefore, this commit fixes not an issue, but a mere inconsistency. This is done in order to avoid developers even considering this edge case.