Implement Unique Quadruplets Finder (Four Sum Problem)

[akarsh-Manodee]

• Added a new class UniqueQuadruplets to solve the Four Sum problem, which finds all unique quadruplets in an array that sum up to a specified target value.
• Implemented the fourSum method that uses sorting and a two-pointer technique to efficiently identify quadruplets.
• Added example test cases in the main method to demonstrate functionality and validate the implementation.
• The solution ensures that duplicate quadruplets are not included in the results by skipping over duplicate values during the iteration.

• [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.
• [ ] 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 :white_check_mark:

Project coverage is 65.97%. Comparing base (3af4cfd) to head (a8683b9).

Additional details and impacted files

@@            Coverage Diff            @@
##             master    #5826   +/-   ##
=========================================
  Coverage     65.96%   65.97%           
- Complexity     4386     4387    +1     
=========================================
  Files           602      602           
  Lines         16783    16783           
  Branches       3226     3226           
=========================================
+ Hits          11071    11072    +1     
  Misses         5266     5266           
+ Partials        446      445    -1     

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[siriak]

We don't add leetcode problems