Add RDAP metric class

The code to use this class will come in future CLs, to avoid a huge CL.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=175162557

java/google/registry/rdap/RdapActionBase.java

@@ -419,7 +419,7 @@ public abstract class RdapActionBase implements Runnable {
         resources,
         (someExcluded && (resources.size() < rdapResultSetMaxSize + 1))
             ? IncompletenessWarningType.MIGHT_BE_INCOMPLETE
-            : IncompletenessWarningType.NONE,
+            : IncompletenessWarningType.COMPLETE,
         numResourcesQueried);
   }
 }