#6724437 Reader: Launch the comprehensive Reader sidebar

Changes proposed in this Pull Request

• Consolidate Reader sidebars to add collapsible menus with site lists for all users.
• Add “Load more sites” button for users with more than 50 site feeds in their Followed Sites

Before

After

Testing instructions

• Switch to this PR, navigate to /read on a user account that is not your Automattic account
• You should see a full sidebar with a collapsible menu of Followed Sites
• On an account with more than 50 subscriptions, ensure you can access all sites in the Followed Sites list by clicking the “Load more sites” button.
• Everything should still work 🙂
• Switch to your Automattic account
• You should see A8C-specific resources (Conversations and Followed Sites) alongside the other options