event_tracer logging inside method.cpp and program.cpp (#346)

Summary:
Pull Request resolved: https://github.com/pytorch/executorch/pull/346

Adding event_tracer logging inside method.cpp and program.cpp.

Similar to D48975975 calls to both `internal::ET_EVENT_TRACER_SCOPE_PROF` and `EXECUTORCH_SCOPE_PROF` are present in `method.cpp` and `program.cpp`. Calls to `event_tracer_*` are a no-op for now and `EXECUTORCH_SCOPE_PROF` will be deprecated soon.

Reviewed By: dbort

Differential Revision: D49220572

fbshipit-source-id: 626246470b40e8eebaf0b9ab9aad61d0835f90de