Add asynchronous scheduled actions to re-save entities

This is used in the domain transfer and delete flows, both of which are
asynchronous flows that have implicit default actions that will be taken at some
point in the future. This CL adds scheduled re-saves to take place soon after
those default actions would become effective, so that they can be re-saved
quickly if so.

Unfortunately the redemption grace period on our TLDs is 35 days, which exceeds
the 30 day maximum task ETA in App Engine, so these won't actually fire.  That's
fine though; the deletion is actually effective as of 5 days, and this is just
removing the grace period.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=201345274

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

@@ -298,6 +298,12 @@
     <url-pattern>/_dr/task/resaveAllEppResources</url-pattern>
   </servlet-mapping>
 
+  <!--  Action to re-save a given entity. -->
+  <servlet-mapping>
+    <servlet-name>backend-servlet</servlet-name>
+    <url-pattern>/_dr/task/resaveEntity</url-pattern>
+  </servlet-mapping>
+
   <!--
     Deletes contacts and hosts enqueued for asynchronous deletion if they are
     not referenced by any domain.

java/google/registry/env/common/default/WEB-INF/queue.xml

@@ -212,6 +212,13 @@
     </retry-parameters>
   </queue>
 
+  <!-- Queue for async actions that should be run at some point in the future. -->
+  <queue>
+    <name>async-actions</name>
+    <rate>1/s</rate>
+    <max-concurrent-requests>5</max-concurrent-requests>
+  </queue>
+
   <!-- The load[0-9] queues are used for load-testing, and can be safely deleted
        in any environment that doesn't require load-testing. -->
   <queue>