feat(Poppperjs): add esm output

packages/vant-popperjs/package.json

@@ -2,8 +2,12 @@
   "name": "@vant/popperjs",
   "version": "1.0.0",
   "description": "Precompiled popperjs core",
-  "main": "lib/index.js",
+  "main": "dist/cjs/index.js",
+  "module": "dist/esm/index.js",
   "types": "lib/index.d.ts",
+  "files": [
+    "dist"
+  ],
   "publishConfig": {
     "access": "public",
     "registry": "https://registry.npmjs.org/"

packages/vant-popperjs/rollup.config.js

@@ -4,9 +4,15 @@ import nodeResolve from '@rollup/plugin-node-resolve';
 
 export default {
   input: path.join(__dirname, 'src', 'index.ts'),
-  output: {
-    dir: 'lib',
+  output: [
+    {
+      dir: 'dist/cjs',
       format: 'cjs',
     },
+    {
+      dir: 'dist/esm',
+      format: 'esm',
+    },
+  ],
   plugins: [nodeResolve(), babel({ babelHelpers: 'runtime' })],
 };

packages/vant-popperjs/tsconfig.json

@@ -1,7 +1,7 @@
 {
   "compilerOptions": {
     "target": "es5",
-    "outDir": "./lib",
+    "outDir": "./dist",
     "module": "ES2015",
     "strict": true,
     "declaration": true,