add calculator feature

[EshaSaha3]

• 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 75.11%. Comparing base (0ff2c06) to head (931937a).

Additional details and impacted files

@@            Coverage Diff            @@
##             master    #6493   +/-   ##
=========================================
  Coverage     75.11%   75.11%           
  Complexity     5575     5575           
=========================================
  Files           687      687           
  Lines         19318    19318           
  Branches       3732     3732           
=========================================
  Hits          14511    14511           
  Misses         4245     4245           
  Partials        562      562           

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[DenizAltunkapan]

A calculator ist not considered as an algorithm. Also, there already exists some kind of calculator:
https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/maths/MathBuilder.java