refactor!: Migrate python code executor tool to autogen-ext

[lspinheiro]

Why are these changes needed?

Related issue number

Closes #4747

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.
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