archives: use separate table

Cleaner to separate things from the backups table.

* icon, appConfig, appStoreIcon etc are only valid for archives
* older version cloudron does not have appConfig in backups table (so it
  cannot be an archive entry)

src/routes/archives.js

@@ -10,7 +10,7 @@ exports = module.exports = {
 };
 
 const assert = require('assert'),
-    { archives } = require('../backups.js'),
+    archives = require('../archives.js'),
     AuditSource = require('../auditsource.js'),
     BoxError = require('../boxerror.js'),
     HttpError = require('connect-lastmile').HttpError,