feat: add Count Set Bits algorithm

[Navadeep0007]

Closes #6931

Description

Implemented algorithm to count total set bits from 1 to N using bit manipulation.

Changes

• Added CountSetBits.java with optimized O(log n) solution
• Added CountSetBitsTest.java with comprehensive test cases
• Included both optimized and naive approaches for comparison

Algorithm Explanation

Uses mathematical approach to count set bits efficiently by:

1. Finding the most significant bit position
2. Counting bits at that position
3. Recursively counting remaining bits

Time Complexity: O(log n)
Space Complexity: O(log n) for recursion stack

[codecov-commenter]

Codecov Report

❌ Patch coverage is 89.47368% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 78.35%. Comparing base (3979e82) to head (0ab23dc).

Files with missing lines	Patch %	Lines
...om/thealgorithms/bitmanipulation/CountSetBits.java	89.47%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #7072      +/-   ##
============================================
- Coverage     78.36%   78.35%   -0.01%     
- Complexity     6690     6691       +1     
============================================
  Files           756      756              
  Lines         22208    22212       +4     
  Branches       4363     4363              
============================================
+ Hits          17403    17405       +2     
- Misses         4106     4107       +1     
- Partials        699      700       +1     

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[Navadeep0007]

@DenizAltunkapan could you please review into my PR,
I appreciate your efforts!

[DenizAltunkapan]

Thank you for your contribution @Navadeep0007