Accessible Tags autocomplete:

- Replace suggest.js with UI Autocomplete.
- Use the same settings like in the editor link toolbar.
- Abstract it and add in a new file, tags-suggest.js. Then make it a dependency for the Tags postbox(es) and Quick and Bulk Edit.
- Add `data-wp-taxonomy` on all input elements to improve handling in the UI for custom taxonomies.

Props afercia, azaozz.
See #33902.
Built from https://develop.svn.wordpress.org/trunk@38797


git-svn-id: http://core.svn.wordpress.org/trunk@38740 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/includes/meta-boxes.php

@@ -431,7 +431,7 @@ function post_tags_meta_box( $post, $box ) {
  	<?php if ( $user_can_assign_terms ) : ?>
 	<div class="ajaxtag hide-if-no-js">
 		<label class="screen-reader-text" for="new-tag-<?php echo $tax_name; ?>"><?php echo $taxonomy->labels->add_new_item; ?></label>
-		<p><input type="text" id="new-tag-<?php echo $tax_name; ?>" name="newtag[<?php echo $tax_name; ?>]" class="newtag form-input-tip" size="16" autocomplete="off" aria-describedby="new-tag-<?php echo $tax_name; ?>-desc" value="" />
+		<p><input data-wp-taxonomy="<?php echo $tax_name; ?>" type="text" id="new-tag-<?php echo $tax_name; ?>" name="newtag[<?php echo $tax_name; ?>]" class="newtag form-input-tip" size="16" autocomplete="off" aria-describedby="new-tag-<?php echo $tax_name; ?>-desc" value="" />
 		<input type="button" class="button tagadd" value="<?php esc_attr_e('Add'); ?>" /></p>
 	</div>
 	<p class="howto" id="new-tag-<?php echo $tax_name; ?>-desc"><?php echo $taxonomy->labels->separate_items_with_commas; ?></p>