调整 api 目录，代码优化

src/router/index.js

@@ -4,7 +4,7 @@ import Config from '@/settings'
 import NProgress from 'nprogress' // progress bar
 import 'nprogress/nprogress.css'// progress bar style
 import { getToken } from '@/utils/auth' // getToken from cookie
-import { buildMenus } from '@/api/menu'
+import { buildMenus } from '@/api/system/menu'
 import { filterAsyncRouter } from '@/store/modules/permission'
 
 NProgress.configure({ showSpinner: false })// NProgress Configuration