Fix NavigationObstacle3D to be attached to navigation map - without it
the NavigationObstacle3D is not working.
Replace radius approximation algorithm with simple "radius" property.
Lots of internal API changes and some docstrings were lost in the conversion.
I manually salvaged many of them but for all the rendering-related ones, an
additional pass is needed.
Added missing enum bindings in BaseMaterial3D and VisualServer.