tests: Migrate PropertyLayer portrayals from dict to PropertyLayerStyle

[Tejasv-Singh]

Migrate Property Layer Visualization to PropertyLayerStyle (Part of #2904)

This PR resolves deprecation warnings related to PropertyLayer visualization by migrating from dictionary-based styles to the PropertyLayerStyle class across both visualization backends and the test suite.

Linked Issue

Part of #2904, Item 1.2 (PropertyLayer Portrayal Dict Deprecation)

Problem

The current test suite and visualization backends were returning plain Python dictionaries for property layer portrayals. This behavior is deprecated and produces DeprecationWarnings because the visualization pipeline now expects PropertyLayerStyle instances.

Implementation

Updated Visualization Backends

Migrated property layer handling in:

mesa/visualization/mpl_space_drawing.py
mesa/visualization/backends/altair_backend.py

Both backends now return PropertyLayerStyle instead of dictionaries.

Updated Tests

Refactored:
tests/test_components_matplotlib.py

tests/test_solara_viz_updated.py
Tests now use the new PropertyLayerStyle API directly, eliminating Solara-specific and Matplotlib-specific warnings.

Code Style Improvements

Renamed unused portrayal callback arguments from layer to _:

def propertylayer_portrayal(_): ...

This follows Python best practices and addresses prior reviewer feedback.

Testing

Ran the targeted test modules:

pytest tests/test_components_matplotlib.py
pytest tests/test_solara_viz_updated.py

Results:

All tests passed

All PropertyLayer-related deprecation warnings are resolved in these modules

Additional Notes

This PR supersedes #2912, which was closed due to merge conflicts.

Fully resolves Item 1.2 from the deprecation migration plan in #2904.

Ensures consistent usage of PropertyLayerStyle across both backends and tests.

[EwoutH]

@Tejasv-Singh Thanks for fixing the PropertyLayer warnings in test_components_matplotlib.py.

However, there's still one PropertyLayer deprecation warning remaining in the test suite:

tests/test_solara_viz_updated.py::test_call_space_drawer
  /home/runner/work/mesa/mesa/mesa/visualization/backends/altair_backend.py:368: FutureWarning: The propertylayer_portrayal dict is deprecated...

This suggests test_solara_viz_updated.py also needs to be updated to use PropertyLayerStyle instead of dictionaries. Would you like to include that fix in this PR?

[Tejasv-Singh]

@EwoutH Yes, absolutely! I will update tests/test_solara_viz_updated.py to use PropertyLayerStyle and push the changes to this PR shortly.

I am also closing the previous PR (#2912) now to avoid any confusion regarding the merge conflicts. This PR will be the main one going forward.

[EwoutH]

Awesome, thanks!

Could you update the PR description to represent the final state of the PR?

[Tejasv-Singh]

Done 🫡