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/ex_getln.c

@@ -6483,7 +6483,7 @@ static int open_cmdwin(void)
     ccline.redraw_state = kCmdRedrawNone;
     ui_call_cmdline_hide(ccline.level);
   }
-  redraw_later(SOME_VALID);
+  redraw_later(curwin, SOME_VALID);
 
   // Save the command line info, can be used recursively.
   save_cmdline(&save_ccline);