The issue was that this menu was only looking at socket templates,
but not at the new node declarations. This fix is to just check those
as well. The fix comes with a small refactor that makes the memory
management a bit simpler.
Differential Revision: https://developer.blender.org/D12866
This just moves a couple of files in `space_node` to C++ and fixes
related errors.
The goal is to be able to use C++ data structures to simplify the code.
Differential Revision: https://developer.blender.org/D11451
