feat: Some improvements for the carousel (changing pages, a11n…)

[g123k]

Hi everyone,

The carousel works when now, but sometimes it moves in all directions when barcodes are detected.
Here are the improvements implements:

• If the selected card is also the barcode scanned => do nothing
• Wait for an animation to be finished, before starting a new one
• There were some specific cases, where the control wouldn't be called to change the page
• The vibration + audio part is now moved to the Scan page, to notify according to the carousel events and not the scanner
• There is also an improvement in terms of a11n: when a barcode is decoded, a voice will tell it

I'm not 100% sure that it will prevent the weird behavior that when a barcode is scanned, sometimes it goes back to the first card. But after my changes, I can't reproduce it anymore, so let's 🤞.

As always, a video is better than words: https://github.com/openfoodfacts/smooth-app/assets/246838/c23c40c2-6f40-4327-81b8-4587050ca80b

[codecov-commenter]

Codecov Report

Merging #4225 (5af9906) into develop (e4a02f8) will decrease coverage by 0.03%.
The diff coverage is 0.00%.

@@             Coverage Diff             @@
##           develop    #4225      +/-   ##
===========================================
- Coverage    10.93%   10.91%   -0.03%     
===========================================
  Files          282      282              
  Lines        14096    14119      +23     
===========================================
- Hits          1542     1541       -1     
- Misses       12554    12578      +24     

Impacted Files	Coverage Δ
...oth_app/lib/data_models/continuous_scan_model.dart	0.00% <ø> (ø)
...es/smooth_app/lib/pages/scan/camera_scan_page.dart	2.12% <ø> (+0.61%)	⬆️
packages/smooth_app/lib/pages/scan/scan_page.dart	2.10% <0.00%> (-0.93%)	⬇️
...mooth_app/lib/widgets/smooth_product_carousel.dart	1.70% <0.00%> (-0.75%)	⬇️

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[teolemon]

If a vibration part is moved to the actual movement on the carousel, how do we know a barcode was scanned ?

[g123k]

We know when a new barcode is scanned when the controller moves to a new page, and not by a swipe gesture.
The callback is called in this specific case

[teolemon]

Merge conflict @g123k