Admin menu: add link to Customizer in sites with block-based theme an…

[monsieur-z]

Fixes https://github.com/Automattic/vulcan/issues/355

Proposed changes:

Until last year, Jetpack provided a way for sites with a block-based theme to include Custom CSS (defined in the Customizer). This feature was removed from the UI but still existed for backward compatibility. As a consequence, site owners of these sites had no visible way of editing existing Custom CSS.

This PR fixes it by ensuring that sites with a block-based theme and custom CSS have a link to the Customizer in the admin menu.

Other information:

• Have you written new tests for your changes, if applicable?
• Have you checked the E2E test CI results, and verified that your changes do not break them?
• Have you tested your changes on WordPress.com, if applicable (if so, you'll see a generated comment below with a script to run)?

Jetpack product discussion

n/a

Does this pull request change what data or activity we track or use?

No.

Testing instructions:

• Spin up a Jetpack test site with this branch
• Ensure the site has a block-based theme (e.g. Twenty Twenty-Four)
• Activate the Custom CSS feature from /wp-admin/admin.php?page=jetpack_modules
• In the Customizer (/wp-admin/customize.php), add some custom CSS (Additional CSS section) and publish it. Leave this tab open.
• From a new tab, deactivate the Custom CSS feature
• Verify that in the admin menu the Appearance item contains an Additional CSS subitem that links to the appropriate section in the Customizer
• Back in the Customizer tab, temporarily remove the custom CSS and publish the changes
• Verify that the Additional CSS item is no longer present under Appearance in the admin menu

[github-actions]

Are you an Automattician? Please test your changes on all WordPress.com environments to help mitigate accidental explosions.

• To test on WoA, go to the Plugins menu on a WordPress.com Simple site. Click on the "Upload" button and follow the upgrade flow to be able to upload, install, and activate the Jetpack Beta plugin. Once the plugin is active, go to Jetpack > Jetpack Beta, select your plugin, and enable the fix/custom-css-block-based-themes branch.

• To test on Simple, run the following command on your sandbox:

  bin/jetpack-downloader test jetpack fix/custom-css-block-based-themes
  

Interested in more tips and information?

• In your local development environment, use the jetpack rsync command to sync your changes to a WoA dev blog.
• Read more about our development workflow here: PCYsg-eg0-p2
• Figure out when your changes will be shipped to customers here: PCYsg-eg5-p2

[github-actions]

Thank you for your PR!

When contributing to Jetpack, we have a few suggestions that can help us test and review your patch:

• ✅ Include a description of your PR changes.
  
• ✅ Add a "[Status]" label (In Progress, Needs Team Review, ...).
  
• ✅ Add testing instructions.
  
• ✅ Specify whether this PR includes any changes to data or privacy.
  
• ✅ Add changelog entries to affected projects
  

This comment will be updated as you work on your PR and make changes. If you think that some of those checks are not needed for your PR, please explain why you think so. Thanks for cooperation 🤖

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The e2e test report can be found here. Please note that it can take a few minutes after the e2e tests checks are complete for the report to be available.

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Once your PR is ready for review, check one last time that all required checks appearing at the bottom of this PR are passing or skipped.
Then, add the "[Status] Needs Team Review" label and ask someone from your team review the code. Once reviewed, it can then be merged.
If you need an extra review from someone familiar with the codebase, you can update the labels from "[Status] Needs Team Review" to "[Status] Needs Review", and in that case Jetpack Approvers will do a final review of your PR.

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Jetpack plugin:

The Jetpack plugin has different release cadences depending on the platform:

• WordPress.com Simple releases happen daily.
• WoA releases happen weekly.
• Releases to self-hosted sites happen monthly. The next release is scheduled for July 2, 2024 (scheduled code freeze on July 1, 2024).

If you have any questions about the release process, please ask in the #jetpack-releases channel on Slack.

[monsieur-z]

WordPress.com Tests are passing after a restart.

[coder-karen]

This tests well for me 👍