feat: 5204 - preliminary step for multi-product price addition

[monsieurtanuki]

What

This is the first step towards multi-product price addition:

• improved flexibility in the "add price page" as now we can change the product (coming next: adding receipt lines, with their own products and amounts)
• creation of a "meta" product, in order to treat in a similar way products from "off" and products from "prices"
• creation of a "product search" page (barcode search), currently with local and server look-ups, with room for many new features

Screenshots

add a price	search a product

Part of

• Replicate the 'Add Receipts' view from the Open Prices web app #5204

Files

New files:

• price_amount_model.dart: Model for the price of a single product.
• price_meta_product.dart: Meta version of a product, coming from OFF or from Prices.
• price_product_search_page.dart: Product Search Page, for Prices.
• price_product_list_tile.dart: Displays a meta product with an action button, as a ListTile.

Impacted files:

• app_en.arb: added 2 labels for the new "price product search" page
• app_fr.arb: added 2 labels for the new "price product search" page
• edit_product_page.dart: minor refactoring
• get_prices_model.dart: minor refactoring
• price_amount_card.dart: minor refactoring
• price_amount_field.dart: minor refactoring
• price_count_widget.dart: minor refactoring
• price_model.dart: moved product amount code to new class PriceAmountModel
• price_product_widget.dart: unrelated UI refactoring
• prices_card.dart: minor refactoring
• product_price_add_page.dart: minor refactoring

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 113 lines in your changes missing coverage. Please review.

Project coverage is 7.42%. Comparing base (4d9c7fc) to head (6bec52a).
Report is 185 commits behind head on develop.

Files	Patch %	Lines
...oth_app/lib/pages/prices/price_product_widget.dart	0.00%	24 Missing ⚠️
..._app/lib/pages/prices/price_product_list_tile.dart	0.00%	23 Missing ⚠️
...mooth_app/lib/pages/prices/price_amount_model.dart	0.00%	17 Missing ⚠️
...h_app/lib/pages/prices/product_price_add_page.dart	0.00%	12 Missing ⚠️
...smooth_app/lib/pages/prices/price_amount_card.dart	0.00%	9 Missing ⚠️
...mooth_app/lib/pages/prices/price_meta_product.dart	0.00%	9 Missing ⚠️
...kages/smooth_app/lib/pages/prices/price_model.dart	0.00%	7 Missing ⚠️
...mooth_app/lib/pages/prices/price_count_widget.dart	0.00%	4 Missing ⚠️
.../smooth_app/lib/pages/prices/get_prices_model.dart	0.00%	3 Missing ⚠️
...mooth_app/lib/pages/prices/price_amount_field.dart	0.00%	2 Missing ⚠️
... and 2 more

Additional details and impacted files

@@            Coverage Diff             @@
##           develop   #5367      +/-   ##
==========================================
- Coverage     9.54%   7.42%   -2.13%     
==========================================
  Files          325     383      +58     
  Lines        16411   19482    +3071     
==========================================
- Hits          1567    1447     -120     
- Misses       14844   18035    +3191     

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[teolemon]

What's the point in making the single price also editable? Can't we hide the pencil in those cases ? Making it possible to switch the barcode mid-course seems like a recipe for user mistakes.

[monsieurtanuki]

What's the point in making the single price also editable? Can't we hide the pencil in those cases ? Making it possible to switch the barcode mid-course seems like a recipe for user mistakes.

The thing is that PR is a preliminary step: if I remove everything with a strong immediate added-value I can close the PR right away.
The next PR will be about adding/removing receipt lines, where the choice of the product will be relevant, and so would the edit button.
For that I need this PR that provides flexibility between the whole receipt and each individual lines.

I can indeed hide the edit button in this PR. Anyway the UI/UX will evolve.

[monsieurtanuki]

@teolemon I've just removed the "edit" button:

[teolemon]

Thank you @monsieurtanuki 👍

[monsieurtanuki]

Thank you @teolemon for your review!

Next step: multi-products! Probably by the end of the week.