添加退出按钮

app/src/main/res/drawable/ic_expand_less.xml

@@ -0,0 +1,9 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="24"
+    android:viewportHeight="24">
+    <path
+        android:fillColor="#FF000000"
+        android:pathData="M12,8l-6,6 1.41,1.41L12,10.83l4.59,4.58L18,14l-6,-6z" />
+</vector>