feat: Remove a maximum of hardcoded sizes and move Padding to Directional ones

[g123k]

Move all EdgeInsets to EdgeInsetsDirectional (to better support RTL)

• replace all default sizes with constants

[codecov-commenter]

Codecov Report

Merging #2534 (99b56e2) into develop (2ea0da3) will decrease coverage by 1.29%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           develop   #2534      +/-   ##
==========================================
- Coverage     8.86%   7.57%   -1.30%     
==========================================
  Files          161     210      +49     
  Lines         6623   10077    +3454     
==========================================
+ Hits           587     763     +176     
- Misses        6036    9314    +3278     

Impacted Files	Coverage Δ
...kages/smooth_app/lib/widgets/attribute_button.dart	0.00% <0.00%> (-92.00%)	⬇️
...s/smooth_app/lib/data_models/user_preferences.dart	8.73% <0.00%> (-23.57%)	⬇️
packages/smooth_app/lib/themes/smooth_theme.dart	60.00% <0.00%> (-22.98%)	⬇️
...p/lib/generic_lib/dialogs/smooth_alert_dialog.dart	15.11% <0.00%> (-19.10%)	⬇️
...mooth_app/lib/data_models/product_preferences.dart	24.65% <0.00%> (-6.78%)	⬇️
packages/smooth_app/lib/main.dart	14.16% <0.00%> (-3.73%)	⬇️
.../smooth_app/lib/pages/onboarding/welcome_page.dart	0.00% <0.00%> (-3.13%)	⬇️
.../smooth_app/lib/pages/onboarding/scan_example.dart	0.00% <0.00%> (-2.28%)	⬇️
...p/lib/pages/onboarding/consent_analytics_page.dart	0.00% <0.00%> (-1.57%)	⬇️
...smooth_app/lib/pages/product/new_product_page.dart	0.00% <0.00%> (-0.88%)	⬇️
... and 221 more

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[M123-dev]

Looks great, thanks @g123k

[teolemon]

Thanks @g123k and thanks @M123-dev for the review