Add LinearRegression Implementation

[Rosander0]

• 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

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.29%. Comparing base (406347c) to head (bdd6b3b).

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #7520      +/-   ##
============================================
+ Coverage     80.25%   80.29%   +0.03%     
- Complexity     7355     7371      +16     
============================================
  Files           810      811       +1     
  Lines         23787    23816      +29     
  Branches       4678     4681       +3     
============================================
+ Hits          19090    19122      +32     
  Misses         3939     3939              
+ Partials        758      755       -3     

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[Rosander0]

Hi @DenizAltunkapan, just checking in on this PR — happy to make any changes if there's feedback, or if it needs anything from me to move forward, let me know.
Also, I'm planning a follow-up contribution once this lands: a Naive Bayes implementation (Multinomial/Bernoulli/Gaussian variants) for the same com.thealgorithms.machinelearning package this PR introduces. Does the proposed package structure here work for that, or would you prefer a different layout before I start on it? Wanted to check before building against a structure that might change.

[DenizAltunkapan]

@Rosander0 thank you for your contribution