Proper heading for admin screens.

First step towards restoring a good heading structure in wp-admin.
The previous `<h1>` contained the site title and a link to the front page and was removed with the toolbar refactoring in 3.2.

Props joedolson, afercia.
Fixes #31650.


Built from https://develop.svn.wordpress.org/trunk@32974


git-svn-id: http://core.svn.wordpress.org/trunk@32945 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/my-sites.php

@@ -56,7 +56,7 @@ if ( $updated ) { ?>
 <?php } ?>
 
 <div class="wrap">
-<h2><?php echo esc_html( $title ); ?></h2>
+<h1><?php echo esc_html( $title ); ?></h1>
 <?php
 if ( empty( $blogs ) ) :
 	echo '<p>';