Async load business hours and blogging prompt blocks

[monsieur-z]

Proposed changes:

Load Business Hours and Blogging Prompt blocks asynchronously. This is a proof-of-concept.

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

• pedMtX-RS-p2
• Block Infrastructure: allow building blocks separately #17099

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

No.

Testing instructions:

Prerequisites

• Pull this Gutenberg PR
• In the jetpack repo, link the Gutenberg plugin to your local folder in tools/docker/jetpack-docker-config-default.yml by adding <path to your Gutenberg folder>: /var/www/html/wp-content/plugins/gutenberg in the volumeMappings key

Testing

TBD

[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 > Jetpack and enable the update/single-block-async-loading branch.

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

  bin/jetpack-downloader test jetpack update/single-block-async-loading
  

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.
  
• ✅ All commits were linted before commit.
  
• ✅ Add a "[Status]" label (In Progress, Needs Team Review, ...).
  
• ✅ Add testing instructions.
  
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• ✅ Add changelog entries to affected projects
  

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---

Jetpack plugin:

• Next scheduled release: August 23, 2023.
• Scheduled code freeze: August 21, 2023.

[monsieur-z]

If we don't need to name bundles, this might as well be:

"_bundles": [
  [ "blogging-prompt", "business-hours" ], // bundled blocks
  "ai-chat" // single block
]

[github-actions]

This PR has been marked as stale. This happened because:

• It has been inactive for the past 3 months.
• It hasn’t been labeled `[Pri] BLOCKER`, `[Pri] High`, etc.

If this PR is still useful, please do a [trunk merge or rebase](https://github.com/Automattic/jetpack/blob/trunk/docs/git-workflow.md#keeping-your-branch-up-to-date) and otherwise make sure it's up to date and has clear testing instructions. You may also want to ping possible reviewers in case they've forgotten about it. Please close this PR if you think it's not valid anymore — if you do, please add a brief explanation.

If the PR is not updated (or at least commented on) in another month, it will be automatically closed.