This PR excises opcheck's dependency on
torch.testing._internal.common_utils, (which comes with dependencies on
expecttest and hypothesis). We do this by moving what we need to
torch.testing._utils and adding a test for it.
Fixes#126870, #126871
Test Plan:
- new tests
Pull Request resolved: https://github.com/pytorch/pytorch/pull/127292
Approved by: https://github.com/williamwen42
ghstack dependencies: #127291
