master: jquery-ui must be fully synchronous

[mrclay]

The solution in #8484 does not cut it (try the forms theme_sandbox page). We need UI's factory function to run fully synchronously. This seems to work:

<?php
$js = file_get_contents(elgg_get_root_path() . "/vendor/bower-asset/jquery-ui/jquery-ui.min.js");

// We must hide define() from jQuery UI in order to reliably run its factory
// function synchronously. If we let it define(), require() does not block and
// allows other scripts to run code before $.ui is available.
?>
//<script>
!function(define) {
    <?= $js ?>
}();
define('jquery-ui', null);

[mrclay]

This fix is in #8513.