refactor(config): migrate configuration files to ES module syntax

- Updated jest.config.js, postcss.config.js, and tailwind.config.js to use ES module export syntax.
- Added "type": "module" to package.json to support ES module imports.
- Refactored copy-tinymce.js to utilize ES module imports and defined __dirname for compatibility.

worklenz-frontend/tailwind.config.js

@@ -1,5 +1,5 @@
 /** @type {import('tailwindcss').Config} */
-module.exports = {
+export default {
   content: ['./src/**/*.{js,jsx,ts,tsx}'],
   theme: {
     extend: {},