[Project Automation] Add artifact url and live gutenberg.run url

[bangank36]

What problem does this address?

A comment should be added to each new PR with the link to live preview sites gutenberg.run
When the preview site is set up, Gutenberg is installed by downloading the ARTIFACT_DOWNLOAD_URL, is it the generated zip from Build Gutenberg Plugin Zip workflow.
So we should create the comment based on the build status of Gutenberg plugin zip

• Last commit
• Status: the artifact build status
• Preview URL: gutenberg.run URL for the PR, in format http://gutenberg.run/${ pr_number }
• Gutenberg plugin zip: the URL of the built file, currently the file is downloaded by accessing Checks tab on the PR

Something like

success	failure	in_progress

What is your proposed solution?

Since the preview site has relied on the Build process , I decided to use workflow_run event to trigger the workflow Pull request automation which will run tasks on Gutenberg project management automation

How the comment is made

• There should be only 01 build notification comment on each PR so we need a placeholder to check whether the comment is made or not, eg: gutenberg-run-placeholder:cmt@v1
• octokit.rest.issues.updateComment or octokit.rest.issues.createComment are used for updating a comment

What is the build status

• There will be 3 status:
  1. in_progress: is when the build workflow has started aka when new PR is made or new commit is pushed to the PR
  2. success: when the workflow_run event has completed and the artifact is available on the API
  3. failure: when the workflow complete but the artifact is not available on the API

How is the plugin file URL is made

• From the Checks tab, the artifact URL is made of ${ repoHtmlUrl }/suites/${ checkSuiteId }/artifacts/${artifact.id}, we can grab those via event payload and from the API
• There is no straightforward way to grab the artifact URL quickly in upload-artifact, as mentioned here or in the action discussions

Reference

• Made a PR Add live preview URL on Pull Request #54303 for early feedbacks
• Prior art
  • GitHub Actions: Add task to comment on PRs with gutenberg.run link. #30149
  • Build Workflow: Add comment with link to plugin zip to PR #28896
• [Project Automation] Add a link to a live preview of a pull request's branch  #27426 Add instructions to PR on how to download the Gutenberg plugin that includes the PR #28881