feat(VExpandTransition): add group prop

[ascott18]

Description

Adds support for VExpandTransition and VExpandXTransition to produce a TransitionGroup.

resolves #19210

Markup:

<template>
  <v-app>
    <v-container>
      <v-btn class="mb-2" color="primary" @click="randomize">Randomize</v-btn>

      <v-row>
        <v-col>
          <h2>v-expand-transition</h2>
          <v-expand-transition group>
            <v-card v-for="item in items" :key="item" :title="item" />
          </v-expand-transition>
        </v-col>
        <v-col>
          <h2>v-expand-x-transition</h2>
          <v-expand-x-transition group>
            <v-card v-for="item in items" :key="'x-' + item" :title="item" class="d-inline-block" />
          </v-expand-x-transition>
        </v-col>
      </v-row>
    </v-container>
  </v-app>
</template>

<script>
  import { ref } from 'vue'
  export default {
    name: 'Playground',
    setup () {
      const items = ref([])

      function randomize () {
        const newItems = []
        const count = 3 + Math.ceil(Math.random() * 3)
        for (let i = 0; i < count; i++) {
          let newNumber
          do {
            newNumber = Math.floor(Math.random() * 10)
          } while (newItems.includes(newNumber))
          newItems[i] = newNumber
        }
        items.value = newItems.sort()
      }

      randomize()

      return {
        items,
        randomize,
      }
    },
  }
</script>