Add Huffman Coding greedy algorithm implementation

[putku45]

Added Huffman Coding greedy algorithm implementation.

Huffman Coding is used for optimal prefix coding and data compression.

Time Complexity: O(n log n)
Space Complexity: O(n)

Reference:
https://en.wikipedia.org/wiki/Huffman_coding

• 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

❌ Patch coverage is 0% with 18 lines in your changes missing coverage. Please review.
✅ Project coverage is 79.35%. Comparing base (9aa2544) to head (1b6caf9).

Files with missing lines	Patch %	Lines
.../thealgorithms/greedyalgorithms/HuffmanCoding.java	0.00%	18 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #7303      +/-   ##
============================================
- Coverage     79.42%   79.35%   -0.08%     
+ Complexity     7062     7061       -1     
============================================
  Files           788      789       +1     
  Lines         23129    23147      +18     
  Branches       4548     4550       +2     
============================================
- Hits          18371    18369       -2     
- Misses         4024     4043      +19     
- Partials        734      735       +1     

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