refactor: Enhance docs, add tests in GenericHashMapUsingArray

[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

Attention: Patch coverage is 90.90909% with 1 line in your changes missing coverage. Please review.

Project coverage is 68.14%. Comparing base (13be250) to head (00b0301).
Report is 3 commits behind head on master.

Files with missing lines	Patch %	Lines
...ures/hashmap/hashing/GenericHashMapUsingArray.java	90.90%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #5972      +/-   ##
============================================
+ Coverage     67.69%   68.14%   +0.44%     
- Complexity     4577     4597      +20     
============================================
  Files           620      620              
  Lines         17145    17119      -26     
  Branches       3311     3307       -4     
============================================
+ Hits          11607    11666      +59     
+ Misses         5093     5010      -83     
+ Partials        445      443       -2     

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