[#17] Add morph client metrics

Signed-off-by: Alejandro Lopez <a.lopez@yadro.com>

pkg/services/tree/metrics.go

@@ -2,6 +2,12 @@ package tree
 
 import "time"
 
+type MetricsRegister interface {
+	AddReplicateTaskDuration(time.Duration, bool)
+	AddReplicateWaitDuration(time.Duration, bool)
+	AddSyncDuration(time.Duration, bool)
+}
+
 type defaultMetricsRegister struct{}
 
 func (defaultMetricsRegister) AddReplicateTaskDuration(time.Duration, bool) {}