Adding imports to metrics helper

Author: jairmyree

sdk/monitor/azure-monitor-query/src/main/java/com/azure/monitor/query/implementation/metrics/models/MetricsHelper.java

@@ -22,6 +22,8 @@
 
 import java.time.Duration;
 import java.time.OffsetDateTime;
+import java.time.ZoneOffset;
+import java.time.format.DateTimeFormatter;
 import java.util.List;
 import java.util.Map;
 import java.util.stream.Collectors;