Changeset 4470 for sites/trunk/wordpress.org/public_html/wp-content/themes/pub/wporg-login/loggedout.php

Login.WordPress.org: Allow user registration through login.wordpress.org

This change does many things, including, but not limited to:

• Making all the routes have proper templates, rather than being template-parts
• Removing all the extra WordPress functionalities and outputs
• Adding the Registration pages and routes
• Updating SSO to handle routes with URL params
• Adding rest endpoints for username/email validation

See #148, #1524