Feature: Decode record before evaluating processor condition

### Feature description

A [processor condition](https://conduit.io/docs/using/processors/conditions) is currently evaluated on the record as-is. If a record has a schema attached and encoded avro data in the payload, it has no access to the data. Conduit should decode the data before passing it to the condition template.

The workaround right now is to use the `field.set` processor to evaluate the condition and set a metadata field with the result, then use that metadata field in the condition on the next processor (the metadata is not encoded and is accessible in the condition).