Vertex tool: add topological points to all editable layers with shared snapped segments

[JuhoErvasti]

Feature description

After #57723 when adding a new feature topological points are added to all editable layers. It would be good if the vertex tool would be consistent with the add feature tool.

This is the current behavior:

A topological point should be added to the other layer's polygon as well.

Here's a test project:
vertex_tool_topopoints.zip

Additional context

I can implement this feature.