Make CodeExecutor Serializable/Declarative

[victordibia]

Why are these changes needed?

Make PythonCodeExecutionTool declarative so it can be used in tools like AGS

Summary of changes

• Make CodeExecutor declarative (convert from Protocol to ABC, inherit from ComponentBase)
• Make LocalCommandLineCodeExecutor, JupyterCodeExecutor and DockerCommandLineCodeExecutor declarative , best effort. Not all fields are serialized, warnings are shown where appropriate.
• Make PythonCodeExecutionTool declarative.

Related issue number

Closes #5526

Checks

• I've included any doc changes needed for https://microsoft.github.io/autogen/. See https://microsoft.github.io/autogen/docs/Contribute#documentation to build and test documentation locally.
• I've added tests (if relevant) corresponding to the changes introduced in this PR.
• I've made sure all auto checks have passed.

Copilot reviewed 5 out of 8 changed files in this pull request and generated no comments.

Files not reviewed (3)

• python/packages/autogen-core/src/autogen_core/code_executor/_base.py: Evaluated as low risk
• python/packages/autogen-ext/src/autogen_ext/tools/code_execution/_code_execution.py: Evaluated as low risk
• python/packages/autogen-ext/src/autogen_ext/code_executors/jupyter/_jupyter_code_executor.py: Evaluated as low risk

[codecov]

Codecov Report

Attention: Patch coverage is 96.34146% with 3 lines in your changes missing coverage. Please review.

Project coverage is 78.74%. Comparing base (4e3b887) to head (7a93796).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...t/src/autogen_ext/code_executors/local/__init__.py	89.47%	2 Missing ⚠️
...ext/code_executors/docker/_docker_code_executor.py	96.15%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5527      +/-   ##
==========================================
+ Coverage   78.36%   78.74%   +0.38%     
==========================================
  Files         167      167              
  Lines        9933    10004      +71     
==========================================
+ Hits         7784     7878      +94     
+ Misses       2149     2126      -23     

Flag	Coverage Δ
unittests	78.74% <96.34%> (+0.38%)	⬆️

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