[nn] Remove deprecated `torch.nn.utils._stateless` (#94498)
Follows https://github.com/pytorch/pytorch/pull/92536#discussion_r1097578900. There have been 10 months since `torch.nn.utils._stateless` was marked as deprecated.
This PR also changes `tie_weights` in `_reparametrize_module` to kw-only argument. Since it is private API and only imported by `torch.nn.utils._stateless` (removed).
Pull Request resolved: https://github.com/pytorch/pytorch/pull/94498
Approved by: https://github.com/jbschlosser
