Add option to auto deploy to docs-latest

[jprochazk]

What

• Add PR check which ensures that the squashed merge commit can be cherry-picked into docs-latest
• Add a job which cherry-picks squashed merge commits from main to docs-latest
• Both run only runs when deploy docs label is present

I believe after this PR, we've got a much better documentation authoring experience, without too much additional complexity. All of these jobs can be easily ripped out if we decide to do something else.

Checklist

• I have read and agree to Contributor Guide and the Code of Conduct
• I've included a screenshot or gif (if applicable)
• I have tested the web demo (if applicable):
  • Using examples from latest main build: rerun.io/viewer
  • Using full set of examples from nightly build: rerun.io/viewer
• The PR title and labels are set such as to maximize their usefulness for the next release's CHANGELOG
• If applicable, add a new check to the release checklist!
• If have noted any breaking changes to the log API in CHANGELOG.md and the migration guide

• PR Build Summary
• Recent benchmark results
• Wasm size tracking

To run all checks from main, comment on the PR with @rerun-bot full-check.

To deploy documentation changes immediately after merging this PR, add the deploy docs label.

[jprochazk]

I decided to do the rest of my testing in a separate repo, so that I could actually push commits to main: https://github.com/jprochazk/ci-playground/actions/workflows/cherry-pick.yml

[github-actions]

Your changes can be cherry-picked to docs-latest and will be deployed
immediately after merging.

[jprochazk]

Check links seems to be failing on main