Add mapper to import domains from RDE deposits

With some additional cleanup by Ben McIlwain.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=146695665

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

@@ -275,6 +275,12 @@
     <url-pattern>/_dr/task/importRdeHosts</url-pattern>
   </servlet-mapping>
 
+  <!-- Mapreduce to import domains from escrow file -->
+  <servlet-mapping>
+    <servlet-name>backend-servlet</servlet-name>
+    <url-pattern>/_dr/task/importRdeDomains</url-pattern>
+  </servlet-mapping>
+
   <!-- Security config -->
   <security-constraint>
     <web-resource-collection>