[jit] __deepcopy__ for `RecursiveScriptModule` (#32684)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/32684
Previously we have `clone` and `clone_instance`, where `clone` will clone both type
and value, and `clone_instance` only clone the value, both of them are shallow copies.
We need to re-evaluate whether we should expose them as a user facing API.
I think we should hide `clone`, but `clone_instance` might be useful as well, especially
when we are copying a model with very large weights, people might just want to do shallow copy.
This PR adds a `deepcopy` that might be useful as a user API, which deep copies the values, including
Tensor, but we didn't deepcopy `Blob`, `Capsule`, `Future` or `PyObject`.
For more discussions please see the following issue.
fixes: https://github.com/pytorch/pytorch/issues/32519
Test Plan: Imported from OSS
Differential Revision: D21220756
fbshipit-source-id: 476bf11fe82c08fac36e7457879a09f545ffdc5e
