Themes: Add filter on bulk action fields.

Because validation was added in [59134] to prevent submitting bulk actions with no selected action, sites that remove or change the default bulk actions can fail due to the missing required inputs. Add a filter (bulk_action_observer_ids) that allows modifying the actions accepted to fulfill validation rules.

Reviewed by Jorbin.
Merges [60186] to the 6.8 branch.

Props ethitter, kabir93, jorbin, davidbaumwald, joedolson.
Fixes #63005.

Built from https://develop.svn.wordpress.org/branches/6.8@60188


git-svn-id: http://core.svn.wordpress.org/branches/6.8@59524 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/js/common.js

@@ -1327,8 +1327,8 @@ $( function() {
 
 		// Observe submissions from posts lists for 'bulk_action' or users lists for 'new_role'.
 		var bulkFieldRelations = {
-			'bulk_action' : 'action',
-			'changeit' : 'new_role'
+			'bulk_action' : window.bulkActionObserverIds.bulk_action,
+			'changeit' : window.bulkActionObserverIds.changeit
 		};
 		if ( ! Object.keys( bulkFieldRelations ).includes( submitterName ) ) {
 			return;