Stop run when an error occured in a group chat

[ekzhu]

Resolves #5851

• Added GroupChatError event type and terminate a run when an error occurs in either a participant or the group chat manager
• Raise a RuntimeError from the error message within the group chat run

[codecov]

Codecov Report

Attention: Patch coverage is 91.35802% with 7 lines in your changes missing coverage. Please review.

Project coverage is 77.26%. Comparing base (86237c9) to head (e04dd5f).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...chat/teams/_group_chat/_base_group_chat_manager.py	87.80%	5 Missing ⚠️
...entchat/teams/_group_chat/_chat_agent_container.py	93.33%	1 Missing ⚠️
...src/autogen_agentchat/teams/_group_chat/_events.py	95.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6141      +/-   ##
==========================================
+ Coverage   77.22%   77.26%   +0.04%     
==========================================
  Files         197      197              
  Lines       13745    13783      +38     
==========================================
+ Hits        10615    10650      +35     
- Misses       3130     3133       +3     

Flag	Coverage Δ
unittests	77.26% <91.35%> (+0.04%)	⬆️

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