Added program to check Smith number

[TaranjeetSinghKalsi]

Added Program to check whether a given number is a Smith Number with testcases.

• 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 78.35%. Comparing base (8a339ef) to head (393e47b).

Additional details and impacted files

@@            Coverage Diff            @@
##             master    #6955   +/-   ##
=========================================
  Coverage     78.35%   78.35%           
- Complexity     6676     6684    +8     
=========================================
  Files           754      755    +1     
  Lines         22191    22203   +12     
  Branches       4356     4360    +4     
=========================================
+ Hits          17387    17398   +11     
- Misses         4105     4106    +1     
  Partials        699      699           

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