Implement sliding window algorithms for fixed and dynamic sizes with tests

[Kesavan-77]

Sliding Windows Algorithm

• Added maxSumSubarrayFixed function to calculate the maximum sum of a fixed-size subarray.
• Added longestSubarrayWithSumAtMost function to find the longest subarray with a sum less than or equal to a given target.
• Included tests for both functions to ensure correctness and edge case handling.
• Updated documentation to reflect the new implementations.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 84.80%. Comparing base (55ff0ad) to head (a3c5ac0).

Additional details and impacted files

@@ Coverage Diff @@## master #1765 +/- ## ========================================== + Coverage 84.76% 84.80% +0.03%  ========================================== Files 378 380 +2 Lines 19738 19785 +47 Branches 2957 2965 +8 ========================================== + Hits 16731 16778 +47  Misses 3007 3007 

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[Kesavan-77]

@raklaptudirm , @appgurueu kindly check the above PR for merging.

[Kesavan-77]

Kindly merge the above PR @raklaptudirm and @appgurueu