update DispatchKey::toString() (#42619)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/42619
Added missing entries to `DispatchKey::toString()` and reordered to match declaration order in `DispatchKey.h`
Test Plan: Imported from OSS
Reviewed By: ezyang
Differential Revision: D22963407
Pulled By: bhosmer
fbshipit-source-id: 34a012135599f497c308ba90ea6e8117e85c74ac
