test: LongestValidParenthesesTest

[alxkm]

Adding tests.
Removed file LongestValidParenthesesTest, which is not java file.

• 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

All modified and coverable lines are covered by tests ✅

Project coverage is 49.97%. Comparing base (7d1847f) to head (8aef5d6).

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #5416      +/-   ##
============================================
+ Coverage     49.87%   49.97%   +0.09%     
- Complexity     3097     3108      +11     
============================================
  Files           524      524              
  Lines         15166    15166              
  Branches       2884     2884              
============================================
+ Hits           7564     7579      +15     
+ Misses         7287     7271      -16     
- Partials        315      316       +1     

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