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 78.27%. Comparing base (e21aee8) to head (dfdfa33).
⚠️ Report is 4 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #6955      +/-   ##
============================================
+ Coverage     78.15%   78.27%   +0.11%     
- Complexity     6503     6573      +70     
============================================
  Files           741      744       +3     
  Lines         21675    21898     +223     
  Branches       4236     4288      +52     
============================================
+ Hits          16940    17140     +200     
- Misses         4063     4074      +11     
- Partials        672      684      +12     

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