Deprecation notices: Allow functionality to be used, and update styles

[coder-karen]

Fixes https://github.com/Automattic/vulcan/issues/511

Proposed changes:

• This PR has two purposes: ensure deprecation notices are easily extendable if there are 1 or more notices to add, and
  modify notice styling depending on design conversation outcomes.
• In terms of styling, the My Jetpack and WP Admin notices will be consistent with style changes, and the Jetpack Settings / Dashboard notices will stay the same until a more complete overhaul of notices is done. Text changes should apply though, which is generally more relevant to the examples given.
• Additional changes include also updating the cookie settings to ensure they work in more environments (removing cookie.serialize), and ensures the WP admin notice only appears on the main WP admin dashboard page.

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

• Design conversation: p1HpG7-uu9-p2

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

No.

Testing instructions:

To test this out, you will need to add in a new notice in a couple of places. This will all be documented in a post once this PR is completed and merged.

• To add the code needed for testing, apply the commented $this->notices example content in the __construct function in class-deprecate.php.
• Add the following function underneath the has_notices function:

private function show_feature_notice() {
	return empty( $_COOKIE['jetpack_deprecate_dismissed']['my-admin-deprecate-feature'] );
}

• In /jetpack/_inc/client/components/jetpack-notices/index.jsx add my-admin-deprecate-feature into const noticeKeys.
• Apply the example notices const within the render function. Change the show value to be true && ! this.isNoticeDismissed( 'my-admin-deprecate-feature' ),
• Make sure to build both Jetpack and My Jetpack: jetpack build plugins/jetpack, jetpack build packages/my-jetpack

Once the code is added, apply this PR locally, and make sure to build Jetpack and the My Jetpack package. Then, test the following areas:

• Jetpack Settings page and Dashboard (only those two pages, not other pages such as/wp-admin/admin.php?page=jetpack_modules).
• WP Admin (only on wp-admin/index.php)
• My Jetpack

Jetpack Settings / Dashboard:

In this case we're only testing wording changes which will be dependant on what is passed through - though there is an example to follow, but the component properties have changed to allow more flexibility - title, link text, for example.

My Jetpack:

WP Admin Dashboard:

[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 🤖

---

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.

---

Follow this PR Review Process:

1. Ensure all required checks appearing at the bottom of this PR are passing.
2. Choose a review path based on your changes:
   • A. Team Review: add the "[Status] Needs Team Review" label
     • For most changes, including minor cross-team impacts.
     • Example: Updating a team-specific component or a small change to a shared library.
   • B. Crew Review: add the "[Status] Needs Review" label
     • For significant changes to core functionality.
     • Example: Major updates to a shared library or complex features.
   • C. Both: Start with Team, then request Crew
     • For complex changes or when you need extra confidence.
     • Example: Refactor affecting multiple systems.
3. Get at least one approval before merging.

Still unsure? Reach out in #jetpack-developers for guidance!

---

Jetpack plugin:

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

• WordPress.com Simple releases happen semi-continuously (PCYsg-Jjm-p2).
• WoA releases happen weekly.
• Releases to self-hosted sites happen monthly. The next release is scheduled for November 5, 2024 (scheduled code freeze on November 4, 2024).

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

[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 update/feature-deprecation-removal-notice branch.

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

  bin/jetpack-downloader test jetpack update/feature-deprecation-removal-notice
  

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