[resubmit] Enable global observers API (#37292)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/37292
After adding c10::DispatchKey::Profiler the behavior of RecordFunction
observers is also controlled by the dispatch key,
this PR moves the logic outside of the profiler into the record function
Reviewed By: jamesr66a
Differential Revision: D21245094
fbshipit-source-id: 595e41b18206d2ba4cf639cb320f630907868b3f
