fix(VTreeview): lines prop supports boolean type

[lzl0304]

Description

fixes #19638

Markup:

<template>
  <v-treeview :items="items" :lines="false" />
</template>

<script>
  export default {
    data: () => ({
      items: [
        {
          id: 1,
          title: 'Applications :',
          children: [
            { id: 2, title: 'Calendar : app' },
            { id: 3, title: 'Chrome : app' },
            { id: 4, title: 'Webstorm : app' },
          ],
        },
      ],
    }),
  }
</script>