Upgrade to Vue 3.x

Summary

What is the current strategy / timeline for upgrading Gridsome to use Vue Next (3.x)?

Request for Basic examples

I would love to see an official statement from the Gridsome team about Vue Next (3.x).

Would be great to have some examples of how to use the Vue Composition API ( related to #1270 ),
and some clear recommendations about when and why to do so.

Motivation

I assume that Gridsome will at some point upgrade to Vue 3.x and as my projects are rather young, I'd like to know how to be as prepared as possible for this (or even to use a Vue 3.x branch from the beginning)