Add tests, add IllegalArgumentException in RodCutting

[Hardvan]

• 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 50.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 58.87%. Comparing base (b54cc21) to head (7680754).
Report is 2 commits behind head on master.

Files with missing lines	Patch %	Lines
...m/thealgorithms/dynamicprogramming/RodCutting.java	50.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #5661      +/-   ##
============================================
+ Coverage     58.59%   58.87%   +0.27%     
- Complexity     3749     3771      +22     
============================================
  Files           554      555       +1     
  Lines         15922    15932      +10     
  Branches       3030     3036       +6     
============================================
+ Hits           9330     9380      +50     
+ Misses         6195     6148      -47     
- Partials        397      404       +7     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.