Use (S)CSS setup from @worpress/scripts

[MAILPOET-5015]

packages/js/components/src/dummy/index.tsx

@@ -1,3 +1,5 @@
+import styles from './style.module.scss';
+
 export function Dummy(): JSX.Element {
-  return <div>Dummy component</div>;
+  return <div className={styles.dummy}>Dummy component</div>;
 }