Added Sliding Window folder with problems

[Shiwangi3003]

Issue#6000 I have added a code of Sliding Window. Kindly review it and merge accordingly.

• [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:

Project coverage is 73.44%. Comparing base (03bb8ee) to head (19f5103).

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #6072      +/-   ##
============================================
+ Coverage     73.42%   73.44%   +0.01%     
  Complexity     5078     5078              
============================================
  Files           656      656              
  Lines         17617    17617              
  Branches       3394     3394              
============================================
+ Hits          12936    12938       +2     
+ Misses         4180     4179       -1     
+ Partials        501      500       -1     

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[siriak]

We don't add leetcode problems