perf($RabbitMQ): make JSON message converter as default

https://docs.spring.io/spring-amqp/reference/html/#async-annotation-conversion

[skip ci]

spring-cloud-starter/src/main/java/com/jmsoftware/maf/springcloudstarter/configuration/RabbitmqConfiguration.java

@@ -3,6 +3,10 @@
 import lombok.extern.slf4j.Slf4j;
 import lombok.val;
 import org.springframework.amqp.core.TopicExchange;
+import org.springframework.amqp.rabbit.connection.ConnectionFactory;
+import org.springframework.amqp.rabbit.core.RabbitTemplate;
+import org.springframework.amqp.support.converter.Jackson2JsonMessageConverter;
+import org.springframework.amqp.support.converter.MessageConverter;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 
@@ -26,4 +30,9 @@ TopicExchange topicExchange() {
         log.info("Created topic exchange: {}", exchange);
         return exchange;
     }
+
+    @Bean
+    public MessageConverter messageConverter() {
+        return new Jackson2JsonMessageConverter();
+    }
 }