Verify correctness of `validate_invariants` method and generate an execution report
We need to verify that this method really checks everything it should do. Like also it does in correct way. Something suspicious is its execution time which takes less than 30s.
Also execution report shall be generated (using standard fc logging functionality) by producing totals for each checked kind of object i.e.:
- verified nn accounts
- verified nn convert requests ...
Collected total_supply is: nn HIVE