feat: add HuffmanCoding with fail-fast validation and immutable design

[singhc7]

Description

This PR implements the Huffman Coding compression algorithm as requested in #6935.

Key Implementation Details:

• Algorithm: Implements a greedy algorithm utilizing a PriorityQueue (min-heap) to build the optimal prefix tree.
• Robustness: Incorporates fail-fast validation to immediately throw exceptions for unsupported characters, malformed binary payloads, and incomplete sequences.
• Safety: Secures the internal dictionary state using Collections.unmodifiableMap to prevent external tampering.
• Testing: Includes a comprehensive JUnit test suite (HuffmanCodingTest.java) covering standard usage, edge cases (nulls, empty strings, single characters), Unicode/special characters, and volume stress tests.

Complexity Analysis

• Time Complexity: $O(n \log k)$, where $n$ is the length of the string and $k$ is the number of unique characters. (In the absolute worst case where all characters are unique, $k = n$, making it $O(n \log n)$).
• Space Complexity: $O(k)$ to store the frequency map, the priority queue, and the resulting Huffman tree structure.

Closes #6935

• 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 88.75000% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 79.40%. Comparing base (023f856) to head (a88aa03).

Files with missing lines	Patch %	Lines
...a/com/thealgorithms/compression/HuffmanCoding.java	88.75%	4 Missing and 5 partials ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #7289      +/-   ##
============================================
+ Coverage     79.37%   79.40%   +0.02%     
- Complexity     7020     7049      +29     
============================================
  Files           786      787       +1     
  Lines         23025    23105      +80     
  Branches       4523     4542      +19     
============================================
+ Hits          18276    18346      +70     
- Misses         4019     4024       +5     
- Partials        730      735       +5     

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