Revise require imports (#3071)

- order (external first)
- remove superfluous file extensions
- new line after imports
- deconstruct (only one time (in `check_config.js`))
- fix path (only one time (in `global-setup.js`))

js/electron.js

@@ -1,8 +1,8 @@
 "use strict";
 
 const electron = require("electron");
-const core = require("./app.js");
-const Log = require("logger");
+const core = require("./app");
+const Log = require("./logger");
 
 // Config
 let config = process.env.config ? JSON.parse(process.env.config) : {};