Add pseudonymization example for the `on_map_failure` parameter

[skykanin]

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IMPORTANT: This issue is reserved as a simple task for git together. Do not solve beforehand.
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We have an examples file showing how to pseudonymize data using this library. However it's missing an example for how to use the on_map_failure parameter when using the with_stable_id method for pseudonymizing data.

Setup

To setup this project locally you will need uv. Then simply uv sync in the project root to fetch all the dependencies.