`Amigo::Retry` errors store error information on the job

The jobs did not store the error_class or error_message (since they didn't hit Sidekiq's retry system). Store whatever the caller provides in the error, so you can provide context like "raise Amigo::Retry::Retry.new(5, "rate limited")to see that the job was rate limited orraise Amigo::Retry::Die("invalid token")` to kill a job because it cannot auth.