1. Show PerDate widgets inside of an PageView
2. Introduce GoRouter so we can intercept back button taps with
BackButtonListener
3. Implement rudimentary navigation
4. Fix bug that still showed a spinner event when the barcode was not
found.
the EnterFoodWidget.
1. Make scanned foods appear in the list of foods
2. Remove Controller for entering food
This commit removes the EnterFoodController that was used to put a
scanned food into the EnterFoodWidget.
This is now unnecessary because scanning a product will be distributed
via the FoodBLoC.
