fix: #2773 - appropriate "clear?" and "delete?" messages for user lists

[monsieurtanuki]

Impacted files:

• app_en.arb: labels for user lists (clear? + delete?)
• app_fr.arb: labels for user lists (clear? + delete?)
• product_list_page.dart: now using the new "clear?" label for user lists
• product_list_user_dialog_helper.dart: now localizing with the new "delete?" label for user lists

What

• The "delete user list?" label was a hard-coded English string: now it's localized.
• There was no "clear user list?" label: now there is.

Screenshot

case	screen
delete user list
clear user list
clear history

Fixes bug(s)

• Fixes: #2773

[codecov-commenter]

Codecov Report

Merging #2778 (348f58e) into develop (2ea0da3) will decrease coverage by 1.73%. The diff coverage is n/a.

@@            Coverage Diff             @@
##           develop   #2778      +/-   ##
==========================================
- Coverage     8.86%   7.12%   -1.74%     
==========================================
  Files          161     218      +57     
  Lines         6623   10650    +4027     
==========================================
+ Hits           587     759     +172     
- Misses        6036    9891    +3855     

Impacted Files	Coverage Δ
...kages/smooth_app/lib/widgets/attribute_button.dart	0.00% <0.00%> (-92.00%)	:arrow_down:
...s/smooth_app/lib/data_models/user_preferences.dart	8.73% <0.00%> (-23.57%)	:arrow_down:
packages/smooth_app/lib/themes/smooth_theme.dart	62.26% <0.00%> (-20.72%)	:arrow_down:
...p/lib/generic_lib/dialogs/smooth_alert_dialog.dart	15.11% <0.00%> (-19.10%)	:arrow_down:
...mooth_app/lib/data_models/product_preferences.dart	21.68% <0.00%> (-9.75%)	:arrow_down:
packages/smooth_app/lib/main.dart	14.65% <0.00%> (-3.24%)	:arrow_down:
.../smooth_app/lib/pages/onboarding/welcome_page.dart	0.00% <0.00%> (-3.13%)	:arrow_down:
.../smooth_app/lib/pages/onboarding/scan_example.dart	0.00% <0.00%> (-2.28%)	:arrow_down:
...ackages/smooth_app/lib/pages/scan/scan_header.dart	2.50% <0.00%> (-2.27%)	:arrow_down:
...p/lib/pages/onboarding/consent_analytics_page.dart	0.00% <0.00%> (-1.57%)	:arrow_down:
... and 237 more

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[monsieurtanuki]

Thank you @VaiTon for your review! I wouldn't vote against your idea of adding an "Are you sure?" title, but I'm not convinced enough to change my PR :)