feat: Settings now use Modal Sheets 🤩

[g123k]

Hi everyone!

I found the preferences too stressing, that's why this PR brings a few changes:

• Generally speaking, there are more margins on the main page
• My efforts were mainly on the App Settings, where I have tried to unify the settings
• All Dropdowns now use a custom Widget that I developed far ago, but that wasn't used anymore
• The new dropdowns use a Modal Sheet to select a value
• Basically, there is no way to have a draggable Modal Sheet directly working on Flutter, hence some ModalRoute & co, that will be reusable for lists for example.

As always, a video: PrefsRevamped.webm

And a few screenshots, just in case:

[codecov-commenter]

Codecov Report

Merging #4307 (281b825) into develop (1cd22a6) will decrease coverage by 0.07%.
The diff coverage is 2.33%.

@@             Coverage Diff             @@
##           develop    #4307      +/-   ##
===========================================
- Coverage    10.80%   10.73%   -0.07%     
===========================================
  Files          287      289       +2     
  Lines        14202    14349     +147     
===========================================
+ Hits          1534     1541       +7     
- Misses       12668    12808     +140     

Impacted Files	Coverage Δ
...generic_lib/bottom_sheets/smooth_bottom_sheet.dart	0.00% <0.00%> (ø)
...b/bottom_sheets/smooth_draggable_bottom_sheet.dart	0.00% <0.00%> (ø)
...om_sheets/smooth_draggable_bottom_sheet_route.dart	0.00% <0.00%> (ø)
...app/lib/generic_lib/widgets/language_selector.dart	0.00% <0.00%> (ø)
packages/smooth_app/lib/pages/image_crop_page.dart	1.00% <ø> (ø)
...oth_app/lib/pages/onboarding/country_selector.dart	0.81% <0.00%> (-0.02%)	⬇️
...ib/pages/preferences/user_preferences_widgets.dart	8.16% <0.00%> (-4.74%)	⬇️
...b/pages/preferences/user_preferences_settings.dart	8.49% <4.10%> (+2.18%)	⬆️
...ib/pages/preferences/user_preferences_account.dart	62.70% <100.00%> (+0.40%)	⬆️
.../pages/preferences/user_preferences_list_tile.dart	100.00% <100.00%> (ø)

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[M123-dev]

Lots of general purpose code which makes sense when moving more and more to bottom sheets, looks great just a conflict

[github-actions]

You can test this PR on: https://app.waldo.com/applications/app-19d476740ba1bb36/sessions

[g123k]

That should be OK for the rebase now