Add admin email verification screen. Shown every six months after an admin has logged in.

Also includes WPCS fixes for wp-login.php.

Props andraganescu, boemedia, lessbloat, azaozz.
See #46349.

git-svn-id: https://develop.svn.wordpress.org/trunk@45757 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/options-general.php

@@ -108,7 +108,7 @@ if ( ! is_multisite() ) {
 <?php } ?>
 
 <tr>
-<th scope="row"><label for="new_admin_email"><?php _e( 'Email Address' ); ?></label></th>
+<th scope="row"><label for="new_admin_email"><?php _e( 'Administration Email Address' ); ?></label></th>
 <td><input name="new_admin_email" type="email" id="new_admin_email" aria-describedby="new-admin-email-description" value="<?php form_option( 'admin_email' ); ?>" class="regular-text ltr" />
 <p class="description" id="new-admin-email-description"><?php _e( 'This address is used for admin purposes. If you change this we will send you an email at your new address to confirm it. <strong>The new address will not become active until confirmed.</strong>' ); ?></p>
 <?php