feat!: Add message context to signature of intervention handler, add more to docs

[jackgerrits]

Breaking:

• This changes the signature of the on_publish and on_send method in the InterventionHandler class to include a message_context parameter instead of an AgentId parameter.

Closes #4003
Related #4349

[codecov]

Codecov Report

Attention: Patch coverage is 80.00000% with 3 lines in your changes missing coverage. Please review.

Project coverage is 68.12%. Comparing base (f4382f0) to head (c703351).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...ges/autogen-core/src/autogen_core/_intervention.py	72.72%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4882      +/-   ##
==========================================
+ Coverage   68.07%   68.12%   +0.04%     
==========================================
  Files         161      161              
  Lines       10172    10179       +7     
==========================================
+ Hits         6925     6934       +9     
+ Misses       3247     3245       -2     

Flag	Coverage Δ
unittests	68.12% <80.00%> (+0.04%)	⬆️

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Copilot reviewed 5 out of 7 changed files in this pull request and generated no comments.

Files not reviewed (2)

• python/packages/autogen-core/docs/src/user-guide/core-user-guide/cookbook/termination-with-intervention.ipynb: Evaluated as low risk
• python/packages/autogen-core/docs/src/user-guide/core-user-guide/cookbook/tool-use-with-intervention.ipynb: Evaluated as low risk