Adding websocket event metrics (#5342)

einterfaces/metrics.go

@@ -26,6 +26,8 @@ type MetricsInterface interface {
 	IncrementMemCacheHitCounter(cacheName string)
 	IncrementMemCacheMissCounter(cacheName string)
 
+	IncrementWebsocketEvent(eventType string)
+
 	AddMemCacheHitCounter(cacheName string, amount float64)
 	AddMemCacheMissCounter(cacheName string, amount float64)
 }