refactor: replace deprecated navigation method ✨ (#1419)

Author: AlgyJr

firestore/app/src/main/java/com/google/firebase/example/fireeats/java/RestaurantDetailFragment.java

@@ -12,6 +12,7 @@
 import androidx.annotation.Nullable;
 import androidx.appcompat.app.AppCompatActivity;
 import androidx.fragment.app.Fragment;
+import androidx.navigation.fragment.NavHostFragment;
 import androidx.recyclerview.widget.LinearLayoutManager;
 
 import com.bumptech.glide.Glide;
@@ -144,7 +145,7 @@ private void onRestaurantLoaded(Restaurant restaurant) {
     }
 
     public void onBackArrowClicked(View view) {
-        requireActivity().onBackPressed();
+        NavHostFragment.findNavController(this).popBackStack();
     }
 
     public void onAddRatingClicked(View view) {

firestore/app/src/main/java/com/google/firebase/example/fireeats/kotlin/RestaurantDetailFragment.kt

@@ -8,6 +8,7 @@ import android.view.View
 import android.view.ViewGroup
 import android.view.inputmethod.InputMethodManager
 import androidx.fragment.app.Fragment
+import androidx.navigation.fragment.findNavController
 import androidx.recyclerview.widget.LinearLayoutManager
 import com.bumptech.glide.Glide
 import com.google.android.gms.tasks.Task
@@ -134,7 +135,7 @@ class RestaurantDetailFragment : Fragment(),
     }
 
     private fun onBackArrowClicked() {
-        requireActivity().onBackPressed()
+        findNavController().popBackStack()
     }
 
     private fun onAddRatingClicked() {