Package up render-all jobs into their own GitHub Actions

[cansavvy]

Render-all has parts of it packaged up, but it should have more of it bundled up for easy updating. Particularly the steps for prepping to leanpub.

https://github.com/ottrproject/OTTR_Template/blob/main/.github/workflows/render-all.yml

I'm picturing a parameter that allows this action to specify whether the rendering should be the standard rendering, the toc-less rendering, or the leanpub rendering.