Add `$depth` parameter to the `nav_menu_css_class`, `nav_menu_item_id`, and `nav_menu_link_attributes` filters.

Fixes #19064
Props cyclometh, chriscct7, johnbillion


git-svn-id: https://develop.svn.wordpress.org/trunk@30358 602fd350-edb4-49c9-b593-d223f7449a82