Deprecate torch.nn.utils.stateless.functional_call (#92280)
This PR:
- Updates the docs to say it is deprecated
- Raises a UserWarning
- Changes most of the callsites inside PyTorch to use
torch.func.functional_call, minus the test_stateless testing.
The motivation behind this is that we can now align behind a single
functional_call API in PyTorch.
Test Plan:
- existing tests
Pull Request resolved: https://github.com/pytorch/pytorch/pull/92280
Approved by: https://github.com/albanD
