Added SubscribeForMetadata() to the sarama client, to access the header field of each received message.

Also replaced TestKafkaClientImplementsKafkaClientIf() with static checks.

For VOL-2207.  Please consider these related patchsets together:
https://gerrit.opencord.org/#/q/VOL-2207

Change-Id: I77f03fbb0ebcdf60cb5f8d0c8c3276325510e874
diff --git a/pkg/kafka/kafka_inter_container_library.go b/pkg/kafka/kafka_inter_container_library.go
index 042e121..8285876 100644
--- a/pkg/kafka/kafka_inter_container_library.go
+++ b/pkg/kafka/kafka_inter_container_library.go
@@ -520,7 +520,7 @@
 		Type:      ic.MessageType_RESPONSE,
 		FromTopic: request.Header.ToTopic,
 		ToTopic:   request.Header.FromTopic,
-		Timestamp: time.Now().Unix(),
+		Timestamp: time.Now().UnixNano(),
 	}
 	responseBody := &ic.InterContainerResponseBody{
 		Success: false,