[feat] add Binary Tree traversal algorithm DFS (Depth First Search)

[inamcodes]

• 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 79.80%. Comparing base (6fbbc94) to head (98dcfae).

Additional details and impacted files

@@            Coverage Diff            @@
##             master    #7450   +/-   ##
=========================================
  Coverage     79.80%   79.80%           
- Complexity     7302     7303    +1     
=========================================
  Files           803      803           
  Lines         23751    23751           
  Branches       4671     4671           
=========================================
  Hits          18955    18955           
  Misses         4036     4036           
  Partials        760      760           

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