BM25 Inverted Index Search Algorithm

[prayas7102]

• 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 80.30303% with 13 lines in your changes missing coverage. Please review.

Please upload report for BASE (master@676d451). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
.../com/thealgorithms/searches/BM25InvertedIndex.java	80.30%	8 Missing and 5 partials ⚠️

Additional details and impacted files

@@            Coverage Diff            @@
##             master    #5615   +/-   ##
=========================================
  Coverage          ?   57.99%           
  Complexity        ?     3656           
=========================================
  Files             ?      546           
  Lines             ?    15738           
  Branches          ?     2992           
=========================================
  Hits              ?     9128           
  Misses            ?     6224           
  Partials          ?      386           

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[siriak]

Looks good, thanks!