vue/no-unused-refs doesn't take Vue 2 Composition API plugin into account

[jacekkarczmarczyk]

Checklist

• I have tried restarting my IDE and the issue persists.
• I have read the FAQ and my problem is not listed.

Tell us about your environment

• ESLint version: 7.27.0
• eslint-plugin-vue version: 7.10.0
• Node version: 4.15.5
• Operating System: win10

Please show your full configuration:

module.exports = {
  extends: [
    'plugin:vue/recommended',
  ],
  plugins: ['vue'],
  rules: {
    'vue/no-unused-refs': 'error',
  },
};

What did you do?

<template>
  <div ref="r" />
</template>

<script>
import { defineComponent, ref, watchEffect } from '@vue/composition-api';

export default defineComponent({
  setup () {
    const r = ref();
    watchEffect(() => console.log(r.value));
    return { r };
  },
});
</script>

What did you expect to happen?
no error

What actually happened?

ESLint: 'r' is defined as ref, but never used.(vue/no-unused-refs)

Repository to reproduce this issue

[ota-meshi]

This issue was fixed in #1556, so close it.