feat(VStepper): add new item-props prop

[johnleider]

Motivation and Context

TODO: add to vertical stepper

closes #20608

Markup:

<template>
  <v-container>
    <v-card color="primary">
      <v-card-title>Stepper with items in slot</v-card-title>

      <v-stepper :model-value="items[2].value">
        <v-stepper-header>
          <v-stepper-item v-for="(item, i) in items" v-bind="item" :key="i" />
        </v-stepper-header>
        <v-stepper-window />
      </v-stepper>
    </v-card>

    <v-card class="mt-4" color="primary">
      <v-card-title>Stepper with :item prop</v-card-title>

      <v-stepper
        :items="items"
        :model-value="items[2].value"
        hide-actions
        item-props
      />
    </v-card>

    <v-card class="mt-4" color="primary">
      <v-card-title>Stepper with :item prop</v-card-title>

      <v-stepper-vertical
        :items="items"
        :model-value="items[2].value"
        hide-actions
        item-props
      />
    </v-card>
  </v-container>
</template>
<script setup lang="ts">
  import { ref } from 'vue'
  import type { VStepperItem } from 'vuetify/components'

  const items = ref([
    {
      value: 'a',
      title: 'Completed with color',
      complete: true,
      color: 'secondary',
    }, {
      value: 'b',
      title: 'Erroneous',
      rules: [() => false],
    }, {
      value: 'c',
      title: 'Disabled current step',
      disabled: true,
    }, {
      value: 'd',
      title: 'Subtitle & custom icon',
      subtitle: 'subtitle',
      icon: 'mdi-car',
    },
  ])
</script>