fixed ColumnarTranspositionCipher and added tests for it

[SAIVARDHAN15]

• 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

Attention: Patch coverage is 0% with 12 lines in your changes missing coverage. Please review.

Project coverage is 54.75%. Comparing base (ee6cd64) to head (9bf2860).
Report is 11 commits behind head on master.

Files with missing lines	Patch %	Lines
...lgorithms/ciphers/ColumnarTranspositionCipher.java	0.00%	12 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #5620      +/-   ##
============================================
+ Coverage     54.73%   54.75%   +0.01%     
- Complexity     3453     3454       +1     
============================================
  Files           538      538              
  Lines         15583    15583              
  Branches       2961     2961              
============================================
+ Hits           8530     8532       +2     
+ Misses         6695     6694       -1     
+ Partials        358      357       -1     

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[siriak]

Please remove main and add JUnit tests

[SAIVARDHAN15]

Please remove main and add JUnit tests

recently, a PR regarding tests for ColumnarTranspositionCipher was merged. So shall I create a PR by just removing the main?