Add SlidingWindowExample class for max sum subarray

[debojyoti10CC]

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• This pull request is all my own work -- I have not plagiarized it.
• All filenames are in PascalCase.
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[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 78.06%. Comparing base (48ba1ae) to head (5f5dd98).

Additional details and impacted files

@@            Coverage Diff            @@
##             master    #6918   +/-   ##
=========================================
  Coverage     78.05%   78.06%           
- Complexity     6466     6467    +1     
=========================================
  Files           738      738           
  Lines         21585    21585           
  Branches       4220     4220           
=========================================
+ Hits          16849    16851    +2     
+ Misses         4064     4063    -1     
+ Partials        672      671    -1     

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