fix(VListGroup): support return-object

[yuwu9145]

Description

fixes #20477

Convert VListGroup.spec.cy.tsx to VListGroup.spec.browser.tsx

Markup:

<template>
  <h1>{{ open }}</h1>
  <v-card class="mx-auto" max-width="300">
    <v-list
      v-model:opened="open"
      :items="items"
      item-value="newValue"
      return-object
    />
  </v-card>
</template>

<script>
  export default {
    data: () => ({
      open: [],
      items: [
        {
          title: 'Item #1',
          newValue: 1,
          children: [
            {
              title: 'Child 1',
              newValue: 100,
            },
          ],
        },
        {
          title: 'Item #2',
          newValue: 2,
        },
        {
          title: 'Item #3',
          newValue: 3,
        },
      ],
    }),
  }
</script>

<template>
  <v-app>
    <v-container>
      <v-treeview :items="items" item-value="id" return-object />
    </v-container>
  </v-app>
</template>

<script setup>
  import { ref } from 'vue'

  const items = ref([
    {
      id: 1,
      title: 'title 1',
      children: [
        {
          id: 2,
          title: 'title 2',
        },
      ],
    },
  ])
</script>

[yuwu9145]

@KaelWD @johnleider Could you briefly check the browser.spec.tsx file being migrated?

[KaelWD]

I think we need to require a primitive item-value anyway to fix return-object matching performance and #19447.

[yuwu9145]

I think we need to require a primitive item-value anyway to fix return-object matching performance and #19447.

• When return-object is applied, the item object must be passed to VListGroup to be able to return the item object to opened.
• nested composable doesn't have return-object state, so it is unable to do primitive item-value matching and return object. But it fully supports item object used as item id.

primitive item-value is cleaner but atm it requires refactoring nested to internally support return-object.

[yuwu9145]

I think we need to require a primitive item-value anyway to fix return-object matching performance and #19447.

@KaelWD If pass primitive item-value, it ends up with three props to be able to get the real "item-key" as well as return the object to v-model:opened, so I came up with a new more straightforward prop "rawId"

The merge-base changed after approval.