Make random button optional for custom apps

[BPerlakiH]

Implements the common code part of: kiwix/kiwix-apple-custom#98

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 46.15385% with 7 lines in your changes missing coverage. Please review.

Project coverage is 23.23%. Comparing base (26d1e3f) to head (b414934).
Report is 9 commits behind head on main.

Files with missing lines	Patch %	Lines
Views/BuildingBlocks/ArticleActions.swift	0.00%	6 Missing ⚠️
Views/Buttons/ArticleShortcutButtons.swift	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1180      +/-   ##
==========================================
- Coverage   24.57%   23.23%   -1.34%     
==========================================
  Files         137      137              
  Lines        7228     7229       +1     
==========================================
- Hits         1776     1680      -96     
- Misses       5452     5549      +97     

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