Add useStore for v3 for vue 2.7 with composition api about vuex HOT 5 OPEN

// utils file
import {getCurrentInstance} from 'vue'
export const useStore = () => {
  const vm = getCurrentInstance();
  if (!vm) throw new Error('must be called in setup');
  return vm.proxy.$store;
};

import { useStore } from '@/utils/index';
const store = useStore();