#7738377 Reading Settings: Add ‘Your homepage displays’ site setting

Proposed Changes

• Add Your homepage displays setting to the new Reading Settings page

  • Display it at the top of the Site settings section

  • Use the GET /sites/$site/dropdown-pages/ endpoint to populate the setting’s dropdown options

  • A page selected in one of the dropdowns should be disabled in another dropdown. E.g.: I have selected About page for Your homepage displays dropdown. Then once I open up the Default posts page dropdown the About page should be disabled.

  • Display an explanation note as:

    Default homepage and posts page content and layout are determined by your active theme. Learn More.

    For now the “Learn more.” link leads to https://wordpress.com/support/templates but there is a new support doc being written up that will replace it when the feature goes out to prod. The following ticket tracks the doc work: Automattic/en.support-docs-content#1805

Testing Instructions

‼️ Be aware that unsetting the Default posts page does not work properly with the component for now due to the following backend issue: #72119

• Apply jetpack’s trunk to your sandbox
• Sandbox public-api.wordpress.com
• Go to http://calypso.localhost:3000/settings/reading/$site, e.g.: http://calypso.localhost:3000/settings/reading/simple-site.blog

Pre-merge Checklist

• Has the general commit checklist been followed? (PCYsg-hS-p2)
• Have you written new tests for your changes?
• Have you tested the feature in Simple (P9HQHe-k8-p2), Atomic (P9HQHe-jW-p2), and self-hosted Jetpack sites (PCYsg-g6b-p2)?
• Have you checked for TypeScript, React or other console errors?
• Have you used memoizing on expensive computations? More info in Memoizing with create-selector and Using memoizing selectors and Our Approach to Data
• Have we added the “[Status] String Freeze” label as soon as any new strings were ready for translation (p4TIVU-5Jq-p2)?
• For changes affecting Jetpack: Have we added the “[Status] Needs Privacy Updates” label if this pull request changes what data or activity we track or use (p4TIVU-ajp-p2)?

Fixes #70409