Add simple thread-safe queue implementation

[prashantpiyush1111]

This PR adds a simple thread-safe queue implementation using Java synchronization.

Features:

• Node-based linked list implementation
• Thread-safe enqueue and dequeue using synchronized methods
• Basic operations: enqueue, dequeue, and isEmpty
• Simple and educational design

Motivation:

This implementation helps demonstrate:

• Mutual exclusion using synchronized
• Avoidance of race conditions
• Behavior of data structures in a multithreaded environment

A simple test example is also included to show multithreaded usage.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 79.57%. Comparing base (763b95b) to head (6ee6b34).

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #7390      +/-   ##
============================================
+ Coverage     79.55%   79.57%   +0.02%     
- Complexity     7178     7194      +16     
============================================
  Files           798      800       +2     
  Lines         23467    23504      +37     
  Branches       4617     4619       +2     
============================================
+ Hits          18668    18703      +35     
- Misses         4054     4055       +1     
- Partials        745      746       +1     

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[JPB17387]

This is just a test comment.

[JPB17387]

This is just a practice/test code review, and I am a very beginner in this.

[JPB17387]

Also this is a test code review