Allow to v-bind the template ref

[ByScripts]

What problem does this feature solve?

When using setup(), it would seems more natural to bind the ref property to the template ref attribute.

Bonus: Allows Ctrl/Cmd Click "Go to declaration" in IDE's :)

What does the proposed API look like?

<template>
  <h1 :ref="titleEl">Here is my title</h1>
</template>

<script>
export default {
  setup() {
    const titleEl = ref();
    return { titleEl };
  }
}
</script>

[ByScripts]

When using <h1 ref="titleEl">, it gives us the sensation of returning an unused property from setup().

[posva]

This was discussed over at vuejs/rfcs#78 on the Template refs section. Having a string also allows dynamic refs.