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

❌ Patch coverage is 98.18182% with 1 line in your changes missing coverage. Please review.
⚠️ Please upload report for BASE (master@fd0bcb7). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
...a/com/thealgorithms/matrix/SearchSortedMatrix.java	97.82%	0 Missing and 1 partial ⚠️

Additional details and impacted files

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