Compared to plain function, arrow function is simpler to understand (without bindings to `this`, `arguments`, `super`) and to read.
Now, plain function will only be used when this object is required.
PR #21691.
Move files/folders renaming functions to core classes.
Query file/folder for renaming by its current path.
Add ability to rename content folders from WebAPI/WebUI.
This cleans up the global namespace by explicitly exporting shared values. All html and JavaScript files have been converted to use explicit exports except for client.js and mocha-init.js
