delete all kinda stuff

delete function implemented
on pressed -> pop up => are you sure about that?
yes: all rating from all pages will be cleared
no: nothing happens, pop closes

lib/providers/spezielleErnaehrungProvider.dart

@@ -20,4 +20,11 @@ class SpezielleErnaehrungProvider extends ChangeNotifier {
     freiText = text;
     notifyListeners();
   }
+
+  void resetAllFields(){
+    freiText = "";
+    ratingSitzmoeglichkeit = 0;
+    ratingKeineAhnung = 0;
+    notifyListeners();
+  }
 }