feat: add K-Nearest Neighbors classification algorithm in machine learning

[Dcyaprogrammer]

Pull Request Template

Description

Implement K-Nearest Neighbors classification algorithm in machine learning

It is a well-known, widely-used and basic classification algorithm that classifies
a data point based on the majority class of its k nearest neighbors.

Related tests ran successfully

Type of change

• New feature (non-breaking change which adds functionality)

Checklist:

• ✅ I ran bellow commands using the latest version of rust nightly.
• ✅ I ran cargo clippy --all -- -D warnings just before my last commit and fixed any issue that was found.
• ✅ I ran cargo fmt just before my last commit.
• ✅ I ran cargo test just before my last commit and all tests passed.
• ✅ I added my algorithm to the corresponding mod.rs file within its own folder, and in any parent folder(s).
• ✅ I added my algorithm to DIRECTORY.md with the correct link.
• ✅ I checked COUNTRIBUTING.md and my code follows its guidelines.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.96%. Comparing base (b705fd7) to head (d33dadb).

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #993      +/-   ##
==========================================
+ Coverage   95.94%   95.96%   +0.01%     
==========================================
  Files         363      364       +1     
  Lines       24721    24810      +89     
==========================================
+ Hits        23719    23809      +90     
+ Misses       1002     1001       -1     

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[Dcyaprogrammer]

Hi @siriak, would you please take a look to your convenience. I believe this is ready to be merged. Thank you!

[siriak]

Looks good, thanks!