feat: 5203 - "add receipt" and "add price tags", even offline or not found

[monsieurtanuki]

What

• This PR introduces the notions of "no product yet" and "product not found" meta-products
• Thanks to "no product yet", we added the "add receipt" and "add price tags" buttons, as we can now start from an empty product list = a list of a single "no product yet" meta-product.
• Thanks to "product not found", we make the server lookup optional.
• As an interesting side-effect, it means that adding prices can now be performed 100% offline. I did try, and it did work!

Screenshots

Additional "add prices" buttons	"no product yet"

cannot find product	product not found

Et voilà:

Fixes bug(s)

• Closes: Replicate the 'Add Multiple products' view from the Open Prices web app #5203

Part of

• Handle cases where the product is not found (for price addition) #5388

Impacted files

• app_en.arb: added 2 "add" and 4 "price product" labels
• app_fr.arb: added 2 "add" and 4 "price product" labels
• edit_product_page.dart: minor refactoring
• get_prices_model.dart: minor refactoring
• price_amount_card.dart: added the case of "no product yet"
• price_amount_model.dart: added "no product yet" check
• price_meta_product.dart: 2 more cases - "no product yet" and "not found product"
• price_product_list_tile.dart: minor refactoring
• price_product_search_page.dart: now we accept "not found" products and we don't force the server lookup
• prices_card.dart: minor refactoring
• product_price_add_page.dart: minor refactoring
• user_preferences_account.dart: added "Add receipt" and "Add price tags"

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 72 lines in your changes missing coverage. Please review.

Project coverage is 7.25%. Comparing base (4d9c7fc) to head (8e45972).
Report is 200 commits behind head on develop.

Files	Patch %	Lines
...mooth_app/lib/pages/prices/price_meta_product.dart	0.00%	29 Missing ⚠️
...pp/lib/pages/prices/price_product_search_page.dart	0.00%	16 Missing ⚠️
...smooth_app/lib/pages/prices/price_amount_card.dart	0.00%	12 Missing ⚠️
...ib/pages/preferences/user_preferences_account.dart	0.00%	10 Missing ⚠️
...mooth_app/lib/pages/prices/price_amount_model.dart	0.00%	4 Missing ⚠️
..._app/lib/pages/prices/price_product_list_tile.dart	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           develop   #5392      +/-   ##
==========================================
- Coverage     9.54%   7.25%   -2.30%     
==========================================
  Files          325     391      +66     
  Lines        16411   20078    +3667     
==========================================
- Hits          1567    1456     -111     
- Misses       14844   18622    +3778     

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[teolemon]

@monsieurtanuki @g123k I would like take the occasion to solve the horrendous low connectivity/ airplane mode experience``, not just for prices, but for products.

We could have a "Add unselected images" only experience, but we could also try to be useful for regular users.

I believe if we want to solve it, we have to write ourselves a script to slice down the daily data exports by country and propose it to the server.

That way, we'll know whether the product actually exists (modulo 2000 products added everyday, plus products that are not tagged as sold in your country, plus other edges cases).
We need to see if we can at least cram the product name, and possibly more (score letters).

What do you think?

[teolemon]

#18

Currently, the solution we have in dev mode would bring the server down

[monsieurtanuki]

@teolemon I would focus on this PR first, as it is remotely related to offline product scan.

Continued conversation in #18 (comment)

[teolemon]

Thanks @monsieurtanuki 👍

[monsieurtanuki]

Thank you @teolemon for your review!

Working on some improvements - and I've found at least one bug (typically when you remove a product).
cf. #5403