refactor(@vant/cli): migrate to ESM package

packages/vant-cli/cjs/shared.cjs

@@ -0,0 +1,23 @@
+const { join, dirname } = require('path');
+const { existsSync } = require('fs');
+
+function findRootDir(dir) {
+  if (existsSync(join(dir, 'vant.config.js'))) {
+    return dir;
+  }
+
+  const parentDir = dirname(dir);
+  if (dir === parentDir) {
+    return dir;
+  }
+
+  return findRootDir(parentDir);
+}
+
+const CWD = process.cwd();
+const ROOT = findRootDir(CWD);
+
+module.exports = {
+  CWD,
+  ROOT,
+};