feat: add notifyChange to Kafka request/response

This method was declared in an internal interface, but when a policy
updates the request and/or response, we need to call it from inside the
policy to ensure the request/response is rebuilt

src/main/java/io/gravitee/gateway/reactive/api/context/kafka/KafkaRequest.java

@@ -30,4 +30,9 @@ public interface KafkaRequest extends NativeRequest {
      * @return the Kafka native request.
      */
     <T extends AbstractRequest> T delegate();
+
+    /**
+     * Register that the request has been updated during its processing and need to be rebuilt before sending it.
+     */
+    void notifyChange();
 }

src/main/java/io/gravitee/gateway/reactive/api/context/kafka/KafkaResponse.java

@@ -30,4 +30,9 @@ public interface KafkaResponse extends NativeResponse {
      * @return the Kafka native response.
      */
     <T extends AbstractResponse> T delegate();
+
+    /**
+     * Register that the response has been updated during its processing and need to be rebuilt before sending it.
+     */
+    void notifyChange();
 }