chore: prefer named exports (#8315)

* chore: prefer named exports

* chore: fix import

src/icon/Icon.tsx

@@ -1,6 +1,6 @@
 import { PropType, defineComponent } from 'vue';
 import { addUnit, createNamespace } from '../utils';
-import Badge from '../badge';
+import { Badge } from '../badge';
 
 const [name, bem] = createNamespace('icon');
 

src/icon/demo/index.vue

@@ -98,7 +98,7 @@ import icons from '@vant/icons';
 import { ref } from 'vue';
 import { useTranslate } from '@demo/use-translate';
 import { RED } from '../../utils/constant';
-import Notify from '../../notify';
+import { Notify } from '../../notify';
 
 // from https://30secondsofcode.org
 function copyToClipboard(str: string) {

src/icon/test/index.spec.js

@@ -1,4 +1,4 @@
-import Icon from '..';
+import { Icon } from '..';
 import { mount } from '../../../test';
 
 test('should render icon with builtin icon name correctly', () => {