Revert "Disable new fragment manager"

This reverts commit 031d051a55.

app/src/main/java/eu/faircode/email/ApplicationEx.java

@@ -37,7 +37,6 @@ import android.os.Looper;
 import android.util.Printer;
 import android.webkit.CookieManager;
 
-import androidx.fragment.app.FragmentManager;
 import androidx.preference.PreferenceManager;
 
 import java.util.Date;
@@ -123,8 +122,6 @@ public class ApplicationEx extends Application {
         WorkerWatchdog.init(this);
         WorkerCleanup.queue(this);
 
-        FragmentManager.enableNewStateManager(false);
-
         registerReceiver(onScreenOff, new IntentFilter(Intent.ACTION_SCREEN_OFF));
 
         if (BuildConfig.DEBUG)