feat: Add Chebyshev Iteration algorithm

[Keykyrios]

Description

This pull request adds an implementation of the Chebyshev Iteration algorithm.

This is an iterative numerical method used to solve systems of linear equations of the form $Ax = b$. It is particularly effective when the matrix $A$ is symmetric positive definite and provides faster convergence than methods like Jacobi or Gauss-Seidel by using Chebyshev polynomials.

This contribution includes:

• src/main/java/com/thealgorithms/maths/ChebyshevIteration.java: The core algorithm implementation with helper methods for vector/matrix operations.
• src/test/java/com/thealgorithms/maths/ChebyshevIterationTest.java: A corresponding set of JUnit 5 tests to validate the implementation, including simple systems, edge cases (e.g., already converged), and invalid input handling.

• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized it.
• All filenames are in PascalCase.
• All functions and variable names follow Java naming conventions.
• All new algorithms have a URL in their comments that points to Wikipedia or other similar explanations.
• All new code is formatted with clang-format -i --style=file path/to/your/file.java

[codecov-commenter]

Codecov Report

❌ Patch coverage is 91.42857% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 78.33%. Comparing base (3c70a54) to head (e36dfd7).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
...va/com/thealgorithms/maths/ChebyshevIteration.java	91.42%	3 Missing and 3 partials ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #6963      +/-   ##
============================================
+ Coverage     78.28%   78.33%   +0.04%     
- Complexity     6581     6602      +21     
============================================
  Files           744      745       +1     
  Lines         21910    21980      +70     
  Branches       4293     4310      +17     
============================================
+ Hits          17153    17217      +64     
- Misses         4074     4077       +3     
- Partials        683      686       +3     

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[alxkm]

Looks good. Thank you for the contribution.