Feature: Use Composition API

[mlmoravek]

Description

Refactor every component into a <script setup> syntax.

Why Oruga need this feature

Even if the Option-API is still a valide Vue API, the Composition-API provides severall improvement (Why Composition API?).

The <script setup> is the recommended syntax for using Composition API inside SFCs. It provides a number of advantages over the normal <script> syntax:

• More succinct code with less boilerplate
• Ability to declare props and emitted events using pure TypeScript
• Better runtime performance (the template is compiled into a render function in the same scope, without an intermediate proxy)
• Better IDE type-inference performance (less work for the language server to extract types from code)

https://vuejs.org/api/sfc-script-setup.html