title: backstack does not clear while navigating from fragment to activity
body: <p>Here is my code</p>
  
  <pre><code>&lt;fragment
    android:id="@+id/fragment1"
    android:name="com.example.app.Fragment1"
    android:label="SignatureFragment"
    tools:layout="@layout/layout_fragment1"&gt;
      &lt;action
        android:id="@+id/action_fragment1_to_main_activity"
        app:destination="@id/main_activity"
        app:enterAnim="@anim/slide_in_from_right"
        app:exitAnim="@anim/no_anim"
        app:launchSingleTop="true"
        app:popEnterAnim="@anim/no_anim"
        app:popExitAnim="@anim/slide_out_to_right"
        app:popUpTo="@id/navigation_graph_id"
        app:popUpToInclusive="true" /&gt;
  &lt;/fragment&gt;
  
  &lt;activity
    android:id="@+id/main_activity"
    android:name="com.example.app.MainActivity"
    android:label="MainActivity"
    tools:layout="@layout/activity_main" /&gt;
  </code></pre>
  
  <p>Now the code for navigation</p>
  
  <pre><code>findNavController().navigate(R.id.action_fragment1_to_main_activity)
  </code></pre>
  
  <p>When I navigate to activity and press back, the <code>fragment</code> is still there. I want to clear the backstack after opening the activity.</p>
  
  <p>I tried to remove the animation and also tried with removing <code>app:launchSingleTop</code>, but no success. </p>