feat(ui)!: emit prompt "messages" as cmdline events #31525

Problem:  Prompts are emitted as messages events, where cmdline events
          are more appropriate. The user input is also emitted as
          message events in fast context, so cannot be displayed with
          vim.ui_attach().
Solution: Prompt for user input through cmdline prompts.

src/nvim/ex_docmd.c

@@ -2201,7 +2201,7 @@ static char *do_one_cmd(char **cmdlinep, int flags, cstack_T *cstack, LineGetter
           errormsg = _("E493: Backwards range given");
           goto doend;
         }
-        if (ask_yesno(_("Backwards range given, OK to swap"), false) != 'y') {
+        if (ask_yesno(_("Backwards range given, OK to swap")) != 'y') {
           goto doend;
         }
       }