feat(VBtn): High Contrast Support (Forced-colors mode)

[06b]

Description

This addresses the request for High Contrast Support #21515 for the VBtn component by adding a border to all v-btns except for the text & plain variant when forced-color mode (For example, High Contrast Mode in Windows) is enabled.

Before:

After:

Markup:

<template>
  <v-row dense>
    <v-col v-for="(variant, i) in variants" :key="i" cols="12" md="4">
      <v-btn :variant="variant" color="primary">
            {{ variant }}
          </v-btn>
    </v-col>
  </v-row>
</template>

<script>
  export default {
    data: () => ({
      variants: ['elevated', 'flat', 'tonal', 'outlined', 'text', 'plain'],
    }),
  }
</script>