feat: add fast exponentiation algorithm

[saahil-mahato]

• [x] I have read CONTRIBUTING.md.
• [x] This pull request is all my own work -- I have not plagiarized it.
• [x] All filenames are in PascalCase.
• [x] All functions and variable names follow Java naming conventions.
• [x] All new algorithms have a URL in their comments that points to Wikipedia or other similar explanations.
• [x] 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 :white_check_mark:

Please upload report for BASE (master@f8397bf). Learn more about missing BASE report.

Additional details and impacted files

@@            Coverage Diff            @@
##             master    #5715   +/-   ##
=========================================
  Coverage          ?   63.74%           
  Complexity        ?     4135           
=========================================
  Files             ?      579           
  Lines             ?    16209           
  Branches          ?     3120           
=========================================
  Hits              ?    10332           
  Misses            ?     5453           
  Partials          ?      424           

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.

[saahil-mahato]

@alxkm Please review this. Thanks.