feat: Ensure Country / Language / Nutrient picker look the same

[g123k]

Hi everyone,

Following the improvements on the country picker (title, list with separators, highlighting search…), here are the same treatment for the language picker and nutrition picker:

[github-actions]

You can test this PR on: Android

[codecov-commenter]

Codecov Report

Merging #4389 (d5176c6) into develop (f9b7b9d) will decrease coverage by 0.01%.
The diff coverage is 0.00%.

@@             Coverage Diff             @@
##           develop    #4389      +/-   ##
===========================================
- Coverage    10.29%   10.28%   -0.01%     
===========================================
  Files          293      293              
  Lines        14752    14762      +10     
===========================================
  Hits          1519     1519              
- Misses       13233    13243      +10     

Files Changed	Coverage Δ
...p/lib/generic_lib/dialogs/smooth_alert_dialog.dart	65.34% <0.00%> (-10.32%)	⬇️
...app/lib/generic_lib/widgets/language_selector.dart	0.00% <0.00%> (ø)
...oth_app/lib/pages/onboarding/country_selector.dart	0.82% <0.00%> (+0.22%)	⬆️
...b/pages/product/nutrition_add_nutrient_button.dart	0.00% <0.00%> (ø)
packages/smooth_app/lib/widgets/smooth_text.dart	0.00% <0.00%> (ø)

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