Adds possibility to get address and port that used by the server

[ksysoev]

This pull request adds a net.Listener field to the Server struct and updates the Run method to use the listener for starting the server. This change allows the server's network address to be retrieved using the new Addr method. Additionally, a new test case has been added to verify the behavior of the Addr method.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 88.46154% with 3 lines in your changes are missing coverage. Please review.

Project coverage is 88.67%. Comparing base (dc190b1) to head (619ff6b).

Files	Patch %	Lines
server/server.go	88.46%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #51      +/-   ##
==========================================
+ Coverage   88.38%   88.67%   +0.29%     
==========================================
  Files          18       18              
  Lines         723      742      +19     
==========================================
+ Hits          639      658      +19     
  Misses         63       63              
  Partials       21       21              

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