add import of custom properties and move uui-css a step out so autoformat does not change the order of imports

src/Umbraco.Web.UI.Client/src/app.ts

@@ -1,4 +1,4 @@
-import '@umbraco-ui/uui-css/dist/uui-css.css';
+import './css/custom-properties.css';
 import 'router-slot';
 
 import { UUIIconRegistryEssential } from '@umbraco-ui/uui';

src/Umbraco.Web.UI.Client/src/index.ts

@@ -1,4 +1,6 @@
+import '@umbraco-ui/uui-css/dist/uui-css.css';
 import 'element-internals-polyfill';
+
 import { startMockServiceWorker } from './mocks/browser';
 
 startMockServiceWorker();