Themed menus: Add a compact version of the cutlist menu.

The compact version is taken from menu_cutlist_compact.xml.  Revert
the addition of menu_cutlist_exit.xml, as there's really no need to
allow such customization.  (Users may want to manually remove
menu_cutlist_exit.xml from their installation directory.)  Add the
ability to take a menu description from an internal string rather than
an external file.  Refs #11533.