Change the entire navigation system.
Remove editor prefix from nav mesh generator class. It is now used for baking
at runtime as well.
Navigation supports obstacle avoidance now with the RVO2 library.
Nav system will also automatically link all nav meshes together to form one
overall complete nav map.
For the time being we don't support writing a description for those, preferring
having all details in the method's description.
Using self-closing tags saves half the lines, and prevents contributors from
thinking that they should write the argument or return documentation there.
(cherry picked from commit 7adf4cc9b5)
We already removed it from the online docs with #35132.
Currently it can only be "Built-In Types" (Variant types) or "Core"
(everything else), which is of limited use.
We might also want to consider dropping it from `ClassDB` altogether
in Godot 4.0.
