Allows to specify transaction phase when firing event through notify 'eventId'

When using EventPublisher.notify to fire an event, the only way to specify a transaction phase is using the overload that receives a Event object, which makes the call a bit more verbose:
notify new Event("eventId", [arg1, arg2] as Object[]), TransactionPhase.XXX

If you do:
notify 'eventId', arg1, arg2, TransactionPhase.XXXX, the transaction phase is treated like an event argument just like arg1 and arg2

I would suggest that notify() is implemented so that if the last element of argument list is a TransactionPhase then it should be excluded from the argument list and treated like an actual TransactionPhase parameter.

Start at EventPublisher.notify and trace the overload that accepts an event identifier and varargs. Check how the final TransactionPhase is currently passed through as an event argument, then add coverage showing that it is treated as the transaction phase while earlier arguments remain event arguments.

Written by the indexing model from the issue text.