Kafka consumer tries to parse JSON CloudEvents twice

[rngcntr]

Whenever a Kafka consumer receives Kafka message that contains a header indicating a CloudEvent (e.g. content-type: application/cloudevents+json), it is parsed to JSON by the ToCloudEvent extension from the CloudNative.CloudEvents.Kafka package already. However, Motor.NET expects the result to be a CloudEvent<byte[]> because it intends to defer the parsing until later.