[ticket/16944] Generate iconify bundle as needed via icons & assets bag

PHPBB3-16944

phpBB/adm/style/simple_footer.html

@@ -21,6 +21,7 @@
 <script src="{T_ASSETS_PATH}/javascript/core.js?assets_version={T_ASSETS_VERSION}"></script>
 
 <!-- EVENT acp_simple_footer_after -->
+{$ICONIFY_ICONS}
 {$SCRIPTS}
 
 {% EVENT acp_simple_footer_body_after %}