build(@vant/lazyload): using rollup to bundle (#9598)

packages/vant-lazyload/rollup.config.js

@@ -0,0 +1,22 @@
+import path from 'path';
+import babel from '@rollup/plugin-babel';
+import nodeResolve from '@rollup/plugin-node-resolve';
+
+export default {
+  input: path.join(__dirname, 'src', 'index.js'),
+  output: [
+    {
+      dir: 'dist/cjs',
+      format: 'cjs',
+    },
+    {
+      dir: 'dist/esm',
+      format: 'esm',
+    },
+  ],
+  external: ['vue', '@vant/use'],
+  plugins: [
+    babel({ babelHelpers: 'bundled', extensions: ['.js', '.ts'] }),
+    nodeResolve(),
+  ],
+};