Milestone M39 - author subscriptions, default thumbnails and more

Let's go through what we got done in Milestone M39 (Jun16 - Jun29).

New Features & Improvements 🚀

✅ Added subscription section to authors page

Added the subscription section to the authors page to keep it consistent with the listing and blog detail pages.

✅ Added logo and default thumbnail support in EUI

The EUI header now shows the logo when it is set. If no logo is available, the blog name will be shown instead. Default thumbnail support has also been added. If no thumbnail is uploaded for a blog post, a fallback thumbnail will be used.

Bug Fixes ⚒️

✅ Fixed spinner position in audit log page

Fixed the spinner on the audit log page to appear centered instead of at the top.

✅ Fix author translation in filters

Fixed the translation issue for the "Author" label in the filters dropdown.

✅ Fixed page title

The admin panel page was missing a proper title, which is now updated to display the correct one.