Fixes (re)parent issues with NavigationObstacle 2D and 3D (same as NavigationAgents).
Also adds the option from NavigationAgents to override the default navigation map.
This makes it easier to spot syntax errors when editing the
class reference. The schema is referenced locally so validation
can still work offline.
Each class XML's schema conformance is also checked on GitHub Actions.
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.
