fix(VInput): add theme class

[SonTT19]

Description

fixes #19598

Markup:

<template>
  <v-app>
    <v-container>
      <v-text-field
        v-model="msg"
        :error-messages="['Error text']"
        theme="dark"
      />
    </v-container>
  </v-app>
</template>

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

  const msg = ref('Hello World!')
</script>

[KaelWD]

Shouldn't this just be on VInput?