Track failed transactions in Paima Engine

[SebastienGllmt]

Right now transactions can fail for a few reasons:

1. The state machine throw an error
2. The SQL command returned by the state machine is invalid
3. Other code related to Paima Engine itself goes wrong (ex: wallet delegation fails)

In #370, we handle these errors. However, we don't actually track anywhere which transaction failed (or why). Eventually though, we'll want to have an explorer for Paima Engine and being able to see that transactions failed will be useful there.