275 preprare backend to hook problems and notifications into alert center front end

[thijsoo]

Context

• We want to add the data we need for the notification ui to the script data.

Summary

This PR can be summarized in the following changelog entry:

• Adds notification and problem information to the script data.

Relevant technical choices:

Test instructions

Test instructions for the acceptance test before the PR gets merged

This PR can be acceptance tested by following these steps:

• Make sure you see a notification in the old dashboard. You can make this happen by resetting your indexables.
• Add the following code to you project: define( 'YOAST_SEO_NEW_DASHBOARD_UI', true );
• Open the console on the new general page and type window.wpseoScriptData.notifications.active And make sure you see a notification in the console only.

Relevant test scenarios

• Changes should be tested with the browser console open
• Changes should be tested on different posts/pages/taxonomies/custom post types/custom taxonomies
• Changes should be tested on different editors (Default Block/Gutenberg/Classic/Elementor/other)
• Changes should be tested on different browsers
• Changes should be tested on multisite

Test instructions for QA when the code is in the RC

• QA should use the same steps as above.

QA can test this PR by following these steps:

Impact check

This PR affects the following parts of the plugin, which may require extra testing:

UI changes

• This PR changes the UI in the plugin. I have added the 'UI change' label to this PR.

Other environments

• This PR also affects Shopify. I have added a changelog entry starting with [shopify-seo], added test instructions for Shopify and attached the Shopify label to this PR.

Documentation

• I have written documentation for this change. For example, comments in the Relevant technical choices, comments in the code, documentation on Confluence / shared Google Drive / Yoast developer portal, or other.

Quality assurance

• I have tested this code to the best of my abilities.
• During testing, I had activated all plugins that Yoast SEO provides integrations for.
• I have added unit tests to verify the code works as intended.
• If any part of the code is behind a feature flag, my test instructions also cover cases where the feature flag is switched off.
• I have written this PR in accordance with my team's definition of done.
• I have checked that the base branch is correctly set.

Innovation

• No innovation project is applicable for this PR.
• This PR falls under an innovation project. I have attached the innovation label.
• I have added my hours to the WBSO document.

Fixes #

[vraja-pro]

CR & AC ✅

[vraja-pro]

• Open the console on the new general page and type window.wpseoScriptData.notifications.active And make sure you see a notification.

This was changed in a later PR. The check should be window.wpseoScriptData.alerts to get all the alerts, problems and notifications, active and dismissed. @hardikgohil7988