bundles/apt: introduce additional_update_commands for updating other stuff

bundles/apt/files/do-unattended-upgrades

@@ -29,6 +29,10 @@ then
 fi
 % endif
 
+% for command in sorted(additional_update_commands):
+${command}
+% endfor
+
 % for affected, restarts in sorted(restart_triggers.items()):
     up_since=$(systemctl show "${affected}" | sed -n 's/^ActiveEnterTimestamp=//p' || echo 0)
     up_since_ts=$(date -d "$up_since" +%s || echo 0)

bundles/apt/items.py

@@ -55,6 +55,7 @@ files = {
         'content_type': 'mako',
         'mode': '0700',
         'context': {
+            'additional_update_commands': node.metadata.get('apt/additional_update_commands', set()),
             'clean_old_kernels': node.metadata.get('apt/clean_old_kernels', True),
             'restart_triggers': node.metadata.get('apt/restart_triggers', {}),
         }