[custom_ops] Block overload names (#106075)
These are valid with the torch.library API, but (1) they add complexity
and (2) I have never seen a custom op actually use an overload name
before. For simplicity we block all overloads.
Test Plan:
- new test
Pull Request resolved: https://github.com/pytorch/pytorch/pull/106075
Approved by: https://github.com/soulitzer
