Update list.php

Fix: unusable pagination in embed colorbox.

View mod/embed/views/defailt/embed/list.php is missing a base_url for navigation.

Function embed_select_tab expects input page to be set, but it isn't.
Adding 'base_url' => elgg_get_site_url() . "embed/" to the options for pagination fixes this

Closes/Fixes/Refs: Issue #6357