GitHub Action for Next.js Test/Live deployment.

[stevector]

I working on a page of documentation describing how to manually or automatically trigger deployments to the Test and Live environments for Next.js (##9724)

I'm not certain if that documentation should encourage site owners to copy/paste what I verified works here: https://github.com/stevector/office-artifacts/blob/345a870642fba423e9360482fb7f716c87f79533/.github/workflows/auto-tag.yml

Or if I should just make a reusable GitHub Action. For now, I'm making this issue so that I can collect input and opinions.