feat(graph): add MergeAccounts utility demonstrating email-based merging

[AlafariAbdullah]

• 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

❌ Patch coverage is 0% with 38 lines in your changes missing coverage. Please review.
✅ Project coverage is 77.84%. Comparing base (8930369) to head (7b3dc8e).

Files with missing lines	Patch %	Lines
...in/java/com/thealgorithms/graph/MergeAccounts.java	0.00%	38 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #6860      +/-   ##
============================================
- Coverage     78.00%   77.84%   -0.16%     
+ Complexity     6444     6443       -1     
============================================
  Files           737      738       +1     
  Lines         21519    21557      +38     
  Branches       4208     4220      +12     
============================================
- Hits          16785    16781       -4     
- Misses         4062     4102      +40     
- Partials        672      674       +2     

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[github-actions]

This pull request has been automatically closed because its workflows or checks failed and it has been inactive for more than 14 days. Please fix the workflows and reopen if you'd like to continue. Merging from main/master alone does not count as activity.