title: How to display back arrow on the first fragment of the second activity
body: <p>I have two activities. Each activity has implemented toolbar with navigation graph. When user is navigated to the second activity in the first fragment there is no back arrow. Is there a way to implement back arrow which would navigate user back to previous activity or do I have to implement my custom toolbar from scratch?</p>
  <pre><code>override fun onCreate(savedInstanceState: Bundle?) {
      super.onCreate(savedInstanceState)
      setContentView(binding.root)
  
      val navHostFragment = supportFragmentManager.findFragmentById(
          R.id.nav_host_activity
      ) as NavHostFragment
      navController = navHostFragment.findNavController()
      
      setSupportActionBar(binding.toolbar)
  
      val appBarConfiguration = AppBarConfiguration.Builder(navController.graph).build()
      setupActionBarWithNavController(navController, appBarConfiguration)
  }
  
  override fun onSupportNavigateUp(): Boolean =
      navController.navigateUp() || super.onSupportNavigateUp()
  </code></pre>