Python API: Adding back-n-forth functionality to map layers

[arjxn-py]

Description

@brookisme & I hacked on this together on 14th August 2025

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📚 Documentation preview: https://jupytergis--877.org.readthedocs.build/en/877/
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[github-actions]

👈 Launch a Binder on branch arjxn-py/jupytergis/hack%2Fpython-ergonomic

[github-actions]

Integration tests report: appsharing.space

[brookisme]

The idea is to create wrapper classes, that add functionality to existing pydantic layers to achive the type of workflow discuss in issue #436.

In particular we want to be able to take the data behind a particular map layer, turn it into a python object (such as a geodataframe), perform programatic manipulations and add a new layer to the map.

Note: To "update" layers we will add the new layer and remove the source layer.