GH-3057: New receiveBatch method on RKCT

Fixes: #3057 

* Adding wrapper method `receiveBatch` in ReactiveKafkaConsumerTemplate
   that delegates to `KafkaReceiver#receiveBatch.` 
* Addressing PR review.

Author: marcusvoltolim

spring-kafka/src/main/java/org/springframework/kafka/core/reactive/ReactiveKafkaConsumerTemplate.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2019-2023 the original author or authors.
+ * Copyright 2019-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -50,6 +50,7 @@
  *
  * @author Mark Norkin
  * @author Adrian Chlebosz
+ * @author Marcus Voltolim
  *
  * @since 2.3.0
  */
@@ -71,6 +72,10 @@ public Flux<ReceiverRecord<K, V>> receive() {
 		return this.kafkaReceiver.receive();
 	}
 
+	public Flux<Flux<ReceiverRecord<K, V>>> receiveBatch() {
+		return this.kafkaReceiver.receiveBatch();
+	}
+
 	public Flux<ConsumerRecord<K, V>> receiveAutoAck() {
 		return this.kafkaReceiver.receiveAutoAck().concatMap(Function.identity());
 	}