register Nodes
Registers command nodes built at runtime rather than by a CommandRegistrar.
All nodes are replayed whenever the dispatcher is rebuilt. Any node name already taken on the dispatcher root - by a built-in command or another provider - fails the whole registration, mirroring the previous addCommand duplicate-name check. Without this, Brigadier would silently merge the node onto the existing root child, overriding its command or grafting grandchildren into it.