[Python] Automatically generate stubs (#2576)

## Motivation and Context
We want to automatically generate stubs in the codegen diff to ensure
they can be reviewed and have a simple way to generate and include the
stubs inside the Maturin wheel.

## Description
The Python example has been moved to the `examples` folder and
refactored. The refactoring
ensures the script `stubgen.py` is included in the codegeneration of the
SDK crate. The script is later used to generate stubs automatically
during testing and can be used by customers to add their own stubs
before the Maturin build

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_By submitting this pull request, I confirm that you can use, modify,
copy, and redistribute this contribution, under the terms of your
choice._

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_By submitting this pull request, I confirm that you can use, modify,
copy, and redistribute this contribution, under the terms of your
choice._

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Signed-off-by: Bigo <1781140+crisidev@users.noreply.github.com>
Co-authored-by: Burak <unexge@gmail.com>