title: use `mapActions` or `mapGetters` with Vuex 4 and Vue 3
body: <p>Anybody knows how to use <code>mapState</code> or <code>mapGetters</code> with <code>Vue 3</code> in the <code>setup</code> function ?
  I know that is possible to use the store with the <code>useStore</code> hook but with this hook We import all the store while with <code>mapState</code> or <code>mapGetters</code> we can specify a <code>module</code> :</p>
  <pre><code>// ...
  
  computed: {
     ...mapGetters('myModule', [
        'myStateVariable'
     ]
  ) 
  
  //...
  </code></pre>