refactor: cleanup RadixSort

[alxkm]

Cleanup RadixSort

Adding test

Update DIRECTORY.md

• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized it.
• All filenames are in PascalCase.
• All functions and variable names follow Java naming conventions.
• All new algorithms have a URL in their comments that points to Wikipedia or other similar explanations.
• All new code is formatted with clang-format -i --style=file path/to/your/file.java

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Please upload report for BASE (master@f1e2606). Learn more about missing BASE report.

Additional details and impacted files

@@            Coverage Diff            @@
##             master    #5280   +/-   ##
=========================================
  Coverage          ?   40.88%           
  Complexity        ?     2520           
=========================================
  Files             ?      519           
  Lines             ?    15452           
  Branches          ?     2945           
=========================================
  Hits              ?     6318           
  Misses            ?     8840           
  Partials          ?      294           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[alxkm]

Hello @vil02, all issues for this PR already fixed (also including negative numbers logic remove), could you please review this PR. Thanks.