feat: add @vant/lazyload pacakge

packages/vant-lazyload/rollup.config.js

@@ -0,0 +1,13 @@
+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: 'lib',
+    format: 'cjs',
+  },
+  external: ['vue'],
+  plugins: [nodeResolve(), babel({ babelHelpers: 'runtime' })],
+};