Added Binary Search Tree with JUnit 5 tests

[RoshanSai07]

This PR adds a Binary Search Tree (BST) implementation in Java under the Trees category, along with comprehensive JUnit 5 tests.

Changes included:

BinarySearchTree.java

• Core operations: insert, delete, search
• Traversals: inorder, preorder, postorder (print)
• Utility functions: findMin(), findMax()
• Traversal methods returning List for testing: inorderList(), preorderList(), postorderList()
• Fully documented with JavaDoc-style comments

BinarySearchTreeTest.java

• Tests insertion, deletion (leaf, one child, two children), search
• Tests findMin and findMax
• Tests inorder, preorder, postorder traversals
• Matches repo style and JUnit 5 conventions

This addition improves the Trees section in the repository, providing a fundamental data structure for search, indexing, and interview/competitive programming applications.

References:
Feature request issue: Closes Status: #6957

• 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 66.00000% with 34 lines in your changes missing coverage. Please review.
✅ Project coverage is 78.20%. Comparing base (a4cf6e3) to head (ced31be).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
.../java/com/thealgorithms/tree/BinarySearchTree.java	66.00%	28 Missing and 6 partials ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #6959      +/-   ##
============================================
- Coverage     78.26%   78.20%   -0.07%     
- Complexity     6567     6597      +30     
============================================
  Files           743      744       +1     
  Lines         21886    21986     +100     
  Branches       4284     4293       +9     
============================================
+ Hits          17129    17194      +65     
- Misses         4074     4102      +28     
- Partials        683      690       +7     

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