Allow control over unexpected failure behavior in processors

Recently we had a problem with a flow using UpdateAttribute that does base64decode, and one of our flow sources began sending invalid base64. This resulted in exceptions in the processor causing rollbacks to the flowfiles and backpressure in the flow.

Since there is no failure relationship to the processor there was no way to resolve this issue, And we realized there are a lot of processors facing this issue where an unexpected failure could cause an infinite loop where some flows may desire to send them to a failure relationship.

I suggest a setting or an unexpected failure relationship, which would allow keeping the existing behavior of a rollback but would also allow terminating or processing the failure in different ways.