Add a command to generate zone data from zoneman

Zone files generated on GCS with this command will be used by a MR (to be implemented in a separate CL) for comparing zone data between zoneman and datastore.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=134134401

java/google/registry/env/common/tools/WEB-INF/web.xml

@@ -140,6 +140,7 @@
     <url-pattern>/_dr/task/generateZoneFiles</url-pattern>
   </servlet-mapping>
 
+
   <!-- Security config -->
   <security-constraint>
     <web-resource-collection>