Blaze: move plugin out of the Jetpack plugin and into package

[jeherve]

Changes proposed in this Pull Request:

This is a follow-up to the following PRs:

• Jetpack Blocks: add new Promoted Posts post-publish panel #27928 introducing the panel
• Blocks: iterate on the design of the Promote post-publish panel #27960 changing the panel's design.

This commit brings in:

• The panel's code from the Jetpack plugin.
  • We change the way we register the panel, so it can be registered outside of the Jetpack plugin; it shouldn't rely on the list of enabled extensions that is managed by the Jetpack plugin.
• The tooling to build the JavaScript bundle in the package.
• The dependencies for it.
• We then enqueue that bundle in the block editor.

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

• 1386-gh-dotcom-forge

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

• No

Testing instructions:

jetpack build packages/promote-posts
jetpack watch packages/promote-posts

• Start on a WordPress.com simple or WoA site that's connected to WordPress.com.
• Switch to this branch, or use the Jetpack Beta plugin to run this branch.
• Add the following in a place that's going to be loaded:

use Automattic\Jetpack\Promote_Posts;
Promote_Posts::configure();

• Go to Posts > Add New
• Publish a post.
• Check the post-publish sidebar panel
• Is the button there?

[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.
  
• ✅ 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 (other than "Required review") 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 you’ve done so, switch to the "[Status] Needs Review" label; someone from Jetpack Crew will then review this PR and merge it to be included in the next Jetpack release.

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Jetpack plugin:

• Next scheduled release: January 3, 2023.
• Scheduled code freeze: December 26, 2022.

[github-actions]

Are you an Automattician? You can now test your Pull Request on WordPress.com. On your sandbox, run bin/jetpack-downloader test jetpack update/blaze-move-package to get started. More details: p9dueE-5Nn-p2

[dereksmart]

The build for the editor needed some sass compiling. Added in fc6a36a

Also added watch functionality in 5c83d74

This is building and testing well

[dereksmart]

Builds and watches working. Merged trunk. Testing well! Will follow up with renaming and enabling on Jetpack