Get the post title.The post title is fetched and if it is blank then a default string is returned. Copied from
wp-admin/includes/template.php, but we can't include that file because: 1. It causes bugs with test fixture generation and strange Docker 255 error codes. 2. It's in the admin; ideally we shouldn't be including files from the admin for a block's output. It's a very small/simple function as well, so duplicating it isn't too terrible.