feat: AVRO with Schema Registry

[brunodomenici]

Hello,

I have a requirement to do AVRO with Schema Registry so, I'm proposing this implementation.

Few things:

• I had to upgrade confluent-kafka-go/v2
• I had to create a struct for Metric object. Confluent's serializer can't serialize map[string]interface{} (Not able to serialize interface types (interface {}) not yet supported (use avrogo instead) confluentinc/confluent-kafka-go#1367)
• This branch is based on Ability to set producer linger.ms and batch.size and producer events logging #135

Thank you