[FIX] headerlib will now hard throw if trying to add files after their respective output function have been used.  Add additional smarty uncaught exception code paths so entire layout won't break in case smarty templates cause exceptions to be thrown.  Use single-spa-css to dynamically load and unload css for toolbar-dialogs, duration-picker and kanban in lib/vue-mf.  This is how CSS should be loaded for vue components from now on.  This commit is likely to cause multiple new error to appear on glitchtip, they are likely not regressions, but previously silent failures to load js or css.  If encountered code must be refactored to call the add_* functions elsewhere.