* feat: 4020 - instant answers for hunger games
New files:
* `background_task_hunger_games.dart`: Background task about answering a hunger games question.
* `random_questions_query.dart`: Robotoff questions helper, for random product questions.
Deleted file:
* `product_question_page.dart`
Impacted files:
* `abstract_background_task.dart`: added "hunger games"
* `background_task_crop.dart`: minor refactoring
* `background_task_details.dart`: minor refactoring
* `background_task_image.dart`: minor refactoring
* `background_task_manager.dart`: simplified the code, as we now always work on tasks with different stamps
* `background_task_refresh.dart`: minor refactoring
* `background_task_unselect.dart`: minor refactoring
* `new_product_page.dart`: minor refactoring
* `offline_data_page.dart`: minor refactoring
* `operation_type.dart`: added a type for "hunger games" background task
* `product_list_import_export.dart`: minor refactoring
* `product_list_page.dart`: minor refactoring
* `product_questions_query.dart`: pre-loads the product if relevant
* `product_questions_widget.dart`: minor refactoring
* `product_refresher.dart`: new standard configuration for product lists; new silent download of product lists; minor refactoring
* `question_card.dart`: now downloading the product only if not in the local database
* `question_page.dart`: now saving the answer with background tasks; refactored
* `questions_query.dart`: refactored as abstract, with code moved to new file `random_questions_query.dart`
* `robotoff_insight_helper.dart`: minor refactoring
* feat: 4020 - unrelated package upgrade
* fix: 4098 - new enum value from iOS 12
