Add Valid Parentheses Checker algorithm

[Jccqt]

Summary of the Change:

This pull request introduces the Valid Parentheses Checker, which checks whether the given parentheses are valid. A valid parentheses should have opening braces and closing braces.

• I have performed a self-review of my code
• My code follows the style guidelines of this project
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Comments in areas I changed are up to date
• I have added comments to hard-to-understand areas of my code
• I have made corresponding changes to the README.md

[codecov]

Codecov Report

Attention: Patch coverage is 86.20690% with 4 lines in your changes missing coverage. Please review.

Project coverage is 95.15%. Comparing base (8fec042) to head (bc160b4).

Files with missing lines	Patch %	Lines
Algorithms/Strings/ValidParentheses.cs	86.20%	3 Missing and 1 partial ⚠️

Additional details and impacted files

@@ Coverage Diff @@ ## master #510 +/- ## ========================================== - Coverage 95.18% 95.15% -0.03%  ========================================== Files 269 270 +1 Lines 10894 10923 +29 Branches 1531 1537 +6 ========================================== + Hits 10369 10394 +25  - Misses 400 403 +3  - Partials 125 126 +1 

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