feat: Add dead callback for conn

[KoNekoD]

In thit PR OnDead callback has been added, its invoked on Connection failure

Just provide in telegram options this callback and it works

[codecov]

Codecov Report

Attention: Patch coverage is 50.00000% with 4 lines in your changes are missing coverage. Please review.

Project coverage is 70.99%. Comparing base (b777b73) to head (1a7623f).
Report is 74 commits behind head on main.

Files	Patch %	Lines
telegram/internal/manager/conn.go	0.00%	1 Missing and 1 partial ⚠️
telegram/pool.go	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1383      +/-   ##
==========================================
- Coverage   71.15%   70.99%   -0.16%     
==========================================
  Files         441      442       +1     
  Lines       17683    17722      +39     
==========================================
  Hits        12582    12582              
- Misses       4168     4203      +35     
- Partials      933      937       +4     

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