api: add API for themes

co-author: hlpr98 <hlpr98@gmail.com> (dict2hlattrs function)

orange is sus??

NOVEMBER DAWN

erase the lie that is redraw_later()

src/nvim/undo.c

@@ -2455,7 +2455,7 @@ static void u_undo_end(
   {
     FOR_ALL_WINDOWS_IN_TAB(wp, curtab) {
       if (wp->w_buffer == curbuf && wp->w_p_cole > 0) {
-        redraw_win_later(wp, NOT_VALID);
+        redraw_later(wp, NOT_VALID);
       }
     }
   }