Add tests, remove main in LowerBound

[Hardvan]

• 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 63.52%. Comparing base (138793d) to head (411af46).

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #5672      +/-   ##
============================================
+ Coverage     63.38%   63.52%   +0.13%     
- Complexity     4090     4097       +7     
============================================
  Files           575      575              
  Lines         16096    16085      -11     
  Branches       3091     3090       -1     
============================================
+ Hits          10203    10218      +15     
+ Misses         5474     5450      -24     
+ Partials        419      417       -2     

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[siriak]

Please fix PR checks

[Hardvan]

Done!