Make DivIcon and CustomIcon work with the new Marker approach by hansthen · Pull Request #2132 · python-visualization/folium

This is a continuation of the PR by @Conengmo.

To make the PR more robust against uses from other flows (like add_child and add_to), we check the ways that we can add children and catch setting the icon there.

The tests for this are included in the playwright_tests branch, for which there is another PR open.