Add missing tests and documentation in Utilities

[reima]

This PR adds tests and documentation for all methods in the Utilities namespace.

• I have performed a self-review of my code
• My code follows the style guidelines of this project
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Comments in areas I changed are up to date
• I have added comments to hard-to-understand areas of my code
• I have made corresponding changes to the README.md

[codecov]

Codecov Report

Base: 95.40% // Head: 95.47% // Increases project coverage by +0.07% 🎉

Coverage data is based on head (317e883) compared to base (a9fa9bf).
Patch has no changes to coverable lines.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #335      +/-   ##
==========================================
+ Coverage   95.40%   95.47%   +0.07%     
==========================================
  Files         192      192              
  Lines        8373     8373              
==========================================
+ Hits         7988     7994       +6     
+ Misses        385      379       -6     

Impacted Files	Coverage Δ
Utilities/Extensions/DictionaryExtensions.cs	100.00% <ø> (ø)
Utilities/Extensions/RandomExtensions.cs	100.00% <ø> (ø)
Algorithms/Sorters/Comparison/TimSorter.cs	96.05% <0.00%> (+0.56%)	⬆️
Utilities/Extensions/VectorExtensions.cs	100.00% <0.00%> (+5.63%)	⬆️

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[siriak]

Looks good, thanks a lot!