Add publish functionality to billing pipeline

This closes the end-to-end billing pipeline, allowing us to share generated detail reports with registrars via Drive and e-mail the invoicing team a link to the generated invoice.

This also factors out the email configs from ICANN reporting into the common 'misc' config, since we'll likely need alert e-mails for future periodic tasks.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=180805972

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

@@ -77,6 +77,14 @@
     <url-pattern>/_dr/task/publishInvoices</url-pattern>
   </servlet-mapping>
 
+  <!--
+    Copies invoice detail reports from GCS to the associated registrar's Drive folder.
+  -->
+  <servlet-mapping>
+    <servlet-name>backend-servlet</servlet-name>
+    <url-pattern>/_dr/task/copyDetailReports</url-pattern>
+  </servlet-mapping>
+
   <!-- ICANN Monthly Reporting -->
 
   <!--