Added Removing stars and complex number multiplication program

[KhushiAgarwal0406]

• 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

[DenizAltunkapan]

@KhushiAgarwal0406 Please fix the failing workflows so I can start the review.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 0% with 19 lines in your changes missing coverage. Please review.
✅ Project coverage is 77.35%. Comparing base (3eb521b) to head (05ec7dd).
⚠️ Report is 34 commits behind head on master.

Files with missing lines	Patch %	Lines
...ava/com/thealgorithms/strings/ComplexMultiply.java	0.00%	10 Missing ⚠️
...in/java/com/thealgorithms/strings/RemoveStars.java	0.00%	9 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #6692      +/-   ##
============================================
+ Coverage     75.80%   77.35%   +1.54%     
- Complexity     5804     6207     +403     
============================================
  Files           705      724      +19     
  Lines         19846    20699     +853     
  Branches       3851     4022     +171     
============================================
+ Hits          15045    16011     +966     
+ Misses         4218     4074     -144     
- Partials        583      614      +31     

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