[Feature request] focus and blur events are missing in next

[the-nightling]

What problem does this feature solve? Restore the focus and blur events that we had in Vue2. Is there any way to access those events?

What does the proposed API look like?

[mengxiong10]

  mounted() {
    document.querySelector('.mx-input').addEventListener('focus', () => {
      console.log('focus');
    });
  },