Allow configuration of media type for kafka publisher

[tandev]

Description
Is seems like the ecotone/kafka does not use the OutputDefaultConversionMediaType in the KafkaPublisherConfiguration for use with MessagePublisher::convertAndSend

It not being passed through to the OutboundMessageConverter being the reason i think because the creation of the converter is hard coded in KafkaOutboundChannelAdapter

$this->outboundMessageConverter = new OutboundMessageConverter($headerMapper);

The other outbound channel implementations using enqueue seem to support this in some capacity.

It would be nice to support this, we would need to send JSON to kafka.

Example

#[EventHandler]
    public function whenSubscriptionWasUpdated(
        OrderWasUpdated $event,

        #[Reference('produce.update')]
        MessagePublisher $messagePublisher
    ): void
    {
        $messagePublisher->convertAndSend(
            new OrderUpdated($event->getOrderId())
        );
    }

will always be converted to serialized php