Use GitHub Action to deploy to GitHub Pages

[TimvdLippe]

Rather than the current Bash scripts, we should use a CI solution like GitHub Actions to deploy. Example action: https://github.com/marketplace/actions/deploy-to-github-pages

[TimvdLippe]

@paulirish you want to take a stab at this, given the scripts run on your machine atm?

[paulirish]

this runs every hour:

cd "$HOME/code/pristine/devtools-protocol/scripts" && ./update-to-latest.sh && ./update-n-publish-docs.sh

basically invoking update-n-publish-docs.sh from a GH action on push for the -protocol repo is an option, but it doesn't feel like it wins us much. the bigger effort is having something like copybara update the -protocol repo with the latest PDF whenever it changes in the chromium repo. if we had that, then the rest of things could sit in actions.