Convert backend to ESM

- About 5 years overdue
- Remove eslint, use bomejs instead

backend/models/setting.js

@@ -1,8 +1,8 @@
 // Objection Docs:
 // http://vincit.github.io/objection.js/
 
-const db    = require('../db');
-const Model = require('objection').Model;
+import { Model } from "objection";
+import db from "../db.js";
 
 Model.knex(db);
 
@@ -27,4 +27,4 @@ class Setting extends Model {
 	}
 }
 
-module.exports = Setting;
+export default Setting;