feat(profile): Add TRANSPILE to MetricName

Add TRANSPILE metric for profiling query transpilation in the unified
query API, used when converting logical plans to target SQL dialects.

Author: dai-chen

core/src/main/java/org/opensearch/sql/monitor/profile/MetricName.java

@@ -10,5 +10,6 @@ public enum MetricName {
   ANALYZE,
   OPTIMIZE,
   EXECUTE,
-  FORMAT
+  FORMAT,
+  TRANSPILE
 }