Accessibility: Make sure layout tables across the admin are correctly linearized.

Adds `role="presentation"` to the `<table>` elements used for layout purposes.

Ideally, HTML tables should be used for tabular data. When tables are used for layout purposes, it's important to remove any native semantics so that assistive technologies can correctly announce the table content in a linearized fashion.

Props greatislander, afercia.
Fixes #46899.
Built from https://develop.svn.wordpress.org/trunk@45403


git-svn-id: http://core.svn.wordpress.org/trunk@45214 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/options-permalink.php

@@ -300,7 +300,7 @@ printf( __( 'If you like, you may enter custom structures for your category and
 ?>
 </p>
 
-<table class="form-table">
+<table class="form-table" role="presentation">
 	<tr>
 		<th><label for="category_base"><?php /* translators: prefix for category permalinks */ _e( 'Category base' ); ?></label></th>
 		<td><?php echo $blog_prefix; ?> <input name="category_base" id="category_base" type="text" value="<?php echo esc_attr( $category_base ); ?>" class="regular-text code" /></td>