pytorch

b3715a86 - Move Lower() method to {Backend}Node (#66749)

Move Lower() method to {Backend}Node (#66749) Move to provide a Lower() method on each node, starting with codegen. Once we delete most non-codegen ops, make this pure-virtual and put Lower() on the remaining non-codegen ops. torch/xla already had Lower() on Node::, and it was removed to enable per-backend customization while sharing Node class. Now that backends have a derived node class, it's convenient to restore Lower() to {BackendNode}