feat(notification): send notification to admin when job failed

[zwpaper]

tested with mock error messages, generated by the background_job::start():

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 35 lines in your changes missing coverage. Please review.

Project coverage is 63.03%. Comparing base (02025aa) to head (eabcb1f).
Report is 22 commits behind head on main.

Files with missing lines	Patch %	Lines
.../tabby-webserver/src/service/background_job/mod.rs	0.00%	35 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3653      +/-   ##
==========================================
- Coverage   63.06%   63.03%   -0.04%     
==========================================
  Files         204      204              
  Lines       23901    23923      +22     
==========================================
+ Hits        15074    15079       +5     
- Misses       8827     8844      +17     

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[wsxiaoys]

Please add link to /jobs/${id} page for the failed job.