Add generic and sorted 2D matrix search utilities

[GziXnine]

• 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 algorithms include a corresponding test class that validates their functionality.
• All new code is formatted with clang-format -i --style=file path/to/your/file.java

Summary

This PR adds two reusable 2D matrix search utilities under com.thealgorithms.matrix.

• SearchSortedMatrix implements Saddleback (“staircase”) search for matrices whose rows and columns are sorted in ascending order, providing an efficient O(m+n) membership check without flattening.
• SearchMatrix provides a general-purpose contains method for arbitrary T[][] matrices with no ordering assumptions, using a straightforward linear scan.

Details

• SearchSortedMatrix

  • Safe handling for null/empty matrices.
  • Validates rectangular (non-jagged) shape and rejects null rows to avoid undefined behavior when the sorted-matrix assumptions are violated.
  • Time O(m+n), space O(1).

• SearchMatrix

  • Works with any object matrix type T[][].
  • Null-safe and supports jagged matrices and null elements via Objects.equals.
  • Time O(m*n), space O(1).

Tests

Adds unit coverage for both algorithms:

• SearchSortedMatrixTest
• SearchMatrixTest

These tests cover typical found/not-found cases and edge conditions (null/empty input, jagged matrices, and null rows/elements where applicable).

Closes #6622

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 79.15%. Comparing base (1b014a2) to head (b1794d9).

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #7217      +/-   ##
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+ Coverage     79.09%   79.15%   +0.06%     
- Complexity     6973     7005      +32     
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  Files           783      785       +2     
  Lines         22950    23017      +67     
  Branches       4512     4536      +24     
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+ Hits          18152    18219      +67     
  Misses         4077     4077              
  Partials        721      721              

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[GziXnine]

Hi @DenizAltunkapan, @yanglbme, @alxkm,

I noticed that my pull request (#7217) has all checks passed, but it still cannot be merged.
Could you please clarify if there is any problem with the PR or anything I need to fix before it can be merged?
I want to make sure it aligns with the repository’s guidelines and standards.

Thank you for your time and guidance!

[github-actions]

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[github-actions]

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