refactor!: 450 - finalizing the breaking changes (#656)

Deleted files:
* `page.dart`: deprecated from 2022-04-20
* `product_list_query_configuration.dart`: deprecated from 2022-08-03
* `to_be_completed_configuration.dart`: deprecated from 2022-08-03

Impacted files:
* `image_helper.dart`: removed code deprecated from 2022-08-18, and so we can get rid of package `image`
* `insight.g.dart`: generated
* `nutriments.dart`: removed 1655 (!) lines of code deprecated from 2022-10-04 - it was not urgent but now seemed a good opportunity
* `nutriments_helper.dart`: removed code deprecated from 2022-10-04 - it was not urgent but now seemed a good opportunity
* `open_food_api_client.dart`: removed code deprecated from 2022-01-22 and 2022-07-26
* `openfoodfacts.dart`: removed export deprecated from 2022-04-20
* `product.dart`: fixed typo
* `product.g.dart`: generated
* `pubspec.yaml`: removed deprecated dependency on `image`; upgraded versions
* `README.md`: added info about how to deal with 2.x.x breaking changes

README.md

@@ -19,6 +19,20 @@ You can find automated code documentation here:  [Documentation](https://openfoo
 - If you can't get the information on a specific product, you can get your user to send photos and data, that will then be processed by Open Food Facts AI and contributors to get the computed result you want to show them.
 - You can also implement the complete flow so that they get immediately the result with some effort on their side.
 
+## Main fixes to apply when dealing with 2.x.x breaking changes.
+
+* Now the only entry point is `import 'package:openfoodfacts/openfoodfacts.dart';`
+  * replace all your instances of `import 'package:openfoodfacts/...';` with a single `import 'package:openfoodfacts/openfoodfacts.dart';` 
+* If you used `State` from `product_state.dart`, you have to rename it to `ProductState`
+* If you used `Level` from `nutrient_levels.dart`, you have to rename it to `NutrientLevel`
+* Removed deprecated classes:
+  * `Page`
+  * `ProductListQueryConfiguration`
+  * `ToBeCompletedConfiguration`
+* Removed deprecated fields and methods in `Nutriments`
+  * _all_ the single nutrient value _fields_ were removed - use `getValue` and `setValue` instead
+  * instead of `getUnit` use `nutrient.typicalUnit`
+
 ## Contributing 
 
 ### If your users do not expect a specific result immediately (eg. Inventory apps)

lib/openfoodfacts.dart

@@ -69,7 +69,6 @@ export 'src/model/user_agent.dart';
 export 'src/model/parameter/allergens_parameter.dart';
 export 'src/model/parameter/barcode_parameter.dart';
 export 'src/model/parameter/ingredients_analysis_parameter.dart';
-export 'src/model/parameter/page.dart';
 export 'src/model/parameter/page_number.dart';
 export 'src/model/parameter/page_size.dart';
 export 'src/model/parameter/pnns_group2_filter.dart';