Replaced unsafe ptr logic with chained split_at_mut in DenseMatrix an…

[jackpots28]

…d DenseMatrixMutView

Fixes #368

Checklist

• [ x ] My branch is up-to-date with development branch.
• [ x ] Everything works and tested on latest stable Rust.
• [ x ] Coverage and Linting have been applied

Current behaviour

Changing DenseMatrix and DenseMatrixMutView that uses unsafe ptr arithmetic for generating mutable iterators

New expected behavior

DenseMatrix and DenseMatrixMutView continue to produce mutable iterators, but uses a "head" / "tail" method + split_at_mut function for iterating

• no test changes required

Change logs

• Replaced unsafe pointer arithmetic in DenseMatrix / DenseMatrixMutView mutable iterators with a safe, chained split_at_mut implementation to ensure memory safety without performance loss.

[Mec-iS]

thank you!

please run cargo fmt --all -- --check and the other checks needed.

[codecov]

Codecov Report

❌ Patch coverage is 27.27273% with 80 lines in your changes missing coverage. Please review.
✅ Project coverage is 44.15%. Comparing base (70d8a0f) to head (64b90c5).
⚠️ Report is 17 commits behind head on development.

Files with missing lines	Patch %	Lines
src/linalg/basic/matrix.rs	27.27%	80 Missing ⚠️

Additional details and impacted files

@@               Coverage Diff               @@
##           development     #371      +/-   ##
===============================================
- Coverage        45.59%   44.15%   -1.45%     
===============================================
  Files               93       94       +1     
  Lines             8034     8097      +63     
===============================================
- Hits              3663     3575      -88     
- Misses            4371     4522     +151     

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[jackpots28]

I updated the formatting and caught the issue with sort_by that clippy complained about. Test coverage is still slightly lower "src/linalg/basic/matrix.rs: 225/364" | "59.72% coverage, 5238/8771 lines covered", should I add some tests for more coverage?