reinplace pass: bugfix for output node replacement (#83845)
Cleaned up some of the arg replacement logic to use tree_map, so it handles FX nodes that have nested containers.
See the added test: when you write a function that returns a list, the `output` node in the FX graph shows up as having `node.args = tuple(immutable_list(...))`
Pull Request resolved: https://github.com/pytorch/pytorch/pull/83845
Approved by: https://github.com/ezyang
