Remove print & main methods, improve comments, add tests in `Floy…

[Hardvan]

…dWarshall.java`

• 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 Uncyclopedia 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 56.17%. Comparing base (f34fe4d) to head (a527e95).
Report is 15 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #5584      +/-   ##
============================================
+ Coverage     54.56%   56.17%   +1.61%     
- Complexity     3413     3549     +136     
============================================
  Files           535      544       +9     
  Lines         15383    15689     +306     
  Branches       2935     2983      +48     
============================================
+ Hits           8393     8814     +421     
+ Misses         6637     6506     -131     
- Partials        353      369      +16     

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[Hardvan]

I have removed the main method as suggested.