Add timestamp() to super stream consumer context

Author: acogoluegnes

src/main/java/com/rabbitmq/stream/impl/SuperStreamConsumer.java

@@ -110,6 +110,11 @@ public long offset() {
               return context.offset();
             }
 
+            @Override
+            public long timestamp() {
+              return context.timestamp();
+            }
+
             @Override
             public void storeOffset() {
               for (ConsumerState state : consumerStates) {