[improvement] rename packages dir to src (#3659)

src/sidebar/index.js

@@ -0,0 +1,19 @@
+import { createNamespace } from '../utils';
+import { ParentMixin } from '../mixins/relation';
+
+const [createComponent, bem] = createNamespace('sidebar');
+
+export default createComponent({
+  mixins: [ParentMixin('vanSidebar')],
+
+  props: {
+    activeKey: {
+      type: [Number, String],
+      default: 0
+    }
+  },
+
+  render(h) {
+    return <div class={[bem(), 'van-hairline--top-bottom']}>{this.slots()}</div>;
+  }
+});