Remove Context from c10 operator schemas (#15312)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/15312
Context will soon be entirely obsolete. Remove it from the operator schema interface.
Reviewed By: dzhulgakov
Differential Revision: D13495323
fbshipit-source-id: caa0f8f092cd6284e510c3e1e3374fe2f8338364
