refactor: Enhance docs, code, add tests in PageRank

[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

❌ Patch coverage is 80.68182% with 17 lines in your changes missing coverage. Please review.
✅ Project coverage is 77.10%. Comparing base (7fb4c8d) to head (cf45be3).

Files with missing lines	Patch %	Lines
...c/main/java/com/thealgorithms/others/PageRank.java	80.68%	15 Missing and 2 partials ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #6642      +/-   ##
============================================
+ Coverage     76.91%   77.10%   +0.18%     
- Complexity     6072     6110      +38     
============================================
  Files           719      719              
  Lines         20398    20437      +39     
  Branches       3951     3952       +1     
============================================
+ Hits          15689    15757      +68     
+ Misses         4114     4081      -33     
- Partials        595      599       +4     

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