refactor: rename Recursion package

[alxkm]

rename package Recursion -> recursion package, remove duplicate class

• 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 ✅

Project coverage is 73.50%. Comparing base (539871a) to head (231b5af).
Report is 2 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #6081      +/-   ##
============================================
+ Coverage     73.46%   73.50%   +0.04%     
+ Complexity     5099     5098       -1     
============================================
  Files           658      657       -1     
  Lines         17637    17625      -12     
  Branches       3394     3393       -1     
============================================
- Hits          12957    12956       -1     
+ Misses         4178     4166      -12     
- Partials        502      503       +1     

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

[siriak]

Looks good, thanks!