fix(VList): Set item value to item if primitive

[Haviles04]

fixes: #21584

Markup:

<template>
  <v-card class="mx-auto" max-width="300">
    <v-list
      v-model:selected="selected"
      :items="items"
      select-strategy="independent"
      selectable
    />
  </v-card>
  <v-card class="mx-auto my-8 pa-4" max-width="300">
    <div>{{ selected }}</div>
  </v-card>
</template>

<script setup>
  import { ref } from 'vue'
  const items = [
    'Lorem ipsum',
    'Foo bar',
    'Avocado toast',
  ]
  const selected = ref([])
</script>