feat: Filterable text: ensure to remove accents when comparing

[g123k]

Hi everyone,

While testing if #4389 was still OK once merged, I totally forgot to support accentuated characters.
For example: Français will be OK when spelled with Francais.

[codecov-commenter]

Codecov Report

Merging #4394 (6edb869) into develop (a08a2f9) will decrease coverage by 0.01%.
The diff coverage is 0.00%.

@@             Coverage Diff             @@
##           develop    #4394      +/-   ##
===========================================
- Coverage    10.29%   10.28%   -0.01%     
===========================================
  Files          293      293              
  Lines        14757    14763       +6     
===========================================
  Hits          1519     1519              
- Misses       13238    13244       +6     

Files Changed	Coverage Δ
...app/lib/generic_lib/widgets/language_selector.dart	0.00% <0.00%> (ø)
...oth_app/lib/pages/onboarding/country_selector.dart	0.80% <0.00%> (-0.03%)	⬇️
packages/smooth_app/lib/widgets/smooth_text.dart	0.00% <0.00%> (ø)

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[github-actions]

You can test this PR on: Android