Improve `TrieImp.java` comments & enhance readability

[Hardvan]

• [x] I have read CONTRIBUTING.md.
• [x] This pull request is all my own work -- I have not plagiarized it.
• [x] All filenames are in PascalCase.
• [x] All functions and variable names follow Java naming conventions.
• [x] All new algorithms have a URL in their comments that points to Wikipedia or other similar explanations.
• [x] 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 :white_check_mark:

Project coverage is 53.32%. Comparing base (be8df21) to head (b77b258).

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #5526      +/-   ##
============================================
+ Coverage     52.95%   53.32%   +0.36%     
- Complexity     3309     3322      +13     
============================================
  Files           529      529              
  Lines         15343    15306      -37     
  Branches       2925     2919       -6     
============================================
+ Hits           8125     8162      +37     
+ Misses         6882     6809      -73     
+ Partials        336      335       -1     

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[Hardvan]

I have removed duplicate comments, main method, and added Junit tests for the Trie algorithm.

[Hardvan]

Thanks!