GitLab

Summary:
Tidy uses of `torch.device` in `Meshes`:
- Allow `str` or `torch.device` in `Meshes.to()` method
- Consistently use `torch.device` for internal type
- Fix comparison of devices

Reviewed By: nikhilaravi

Differential Revision: D28969461

fbshipit-source-id: 16d3c1f5458954bb11fdf0efea88542e94dccd7a