Support for SSL for the connection to Schema Registry is needed

[whatsupbros]

Support for SSL certificates and keystores configuration options for the connection to Schema Registry is needed.

Currently, this is not possible to connect to Schema Registry, requiring client SSL certificate, with libserdes:

$ ./kafkacat -b $KAFKA_BROKER_HOST:$KAFKA_BROKER_PORT \
> -t my-topic \
> -s value=avro \
> -r https://$KAFKA_API_KEY:$KAFKA_API_SECRET@$KAFKA_SCHEMA_REGISTRY_HOST:$KAFKA_SCHEMA_REGISTRY_PORT \
> -X security.protocol=SASL_SSL \
> -X sasl.mechanisms=PLAIN \
> -X sasl.username="$KAFKA_API_KEY" -X sasl.password="$KAFKA_API_SECRET" \
> -X ssl.keystore.location=$KAFKA_KEYSTORE_P12_LOCATION \
> -X ssl.keystore.password=$KAFKA_KEYSTORE_PASSPHRASE \
> -X ssl.key.password=$KAFKA_KEY_PASSPHRASE \
> -X enable.ssl.certificate.verification=false \
> -o beginning -C
% ERROR: Failed to format message in my-topic [0] at offset 2: Avro/Schema-registry message deserialization: REST request failed (code -1): HTTP request failed: SSL connect error : terminating