add file preview

Reviewed-on: sites/file-explorer#6

assets/controllers/upload_file_controller.js

@@ -2,7 +2,6 @@ import { Controller } from '@hotwired/stimulus';
 
 export default class extends Controller {
     connect() {
-        console.log(this.element);
         this.element.querySelector('input').addEventListener('change', () => {
             this.element.querySelector('button[type="submit"]').click();
         });