feat: Implementing Rabin-Karp algorithm for substring search

[Rudrajiii]

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Describe your change:

• Add an algorithm?
• Fix a bug or typo in an existing algorithm?
• Documentation change?

Checklist:

• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized.
• I know that pull requests will not be merged if they fail the automated tests.
• This PR only changes one algorithm file. To ease review, please open separate PRs for separate algorithms.
• All new JavaScript files are placed inside an existing directory.
• All filenames should use the UpperCamelCase (PascalCase) style. There should be no spaces in filenames.
  Example:UserProfile.js is allowed but userprofile.js,Userprofile.js,user-Profile.js,userProfile.js are not
• All new algorithms have a URL in their comments that points to Wikipedia or another similar explanation.
• If this pull request resolves one or more open issues then the commit message contains Fixes: #{$ISSUE_NO}.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 97.72727% with 2 lines in your changes missing coverage. Please review.

Project coverage is 84.82%. Comparing base (55ff0ad) to head (91113a3).

Files with missing lines	Patch %	Lines
String/RabinKarp.js	97.72%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1757      +/-   ##
==========================================
+ Coverage   84.76%   84.82%   +0.05%     
==========================================
  Files         378      379       +1     
  Lines       19738    19826      +88     
  Branches     2957     2969      +12     
==========================================
+ Hits        16731    16817      +86     
- Misses       3007     3009       +2     

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[Rudrajiii]

@appgurueu @raklaptudirm

[appgurueu]

This already exists: https://github.com/TheAlgorithms/JavaScript/blob/master/Search/RabinKarp.js, should perhaps be moved to string.

[Rudrajiii]

@appgurueu thank you for your review sir !! will add some new algo soon :)