Adding logging for program outputs and delegates (#1276)

Summary:
Pull Request resolved: https://github.com/pytorch/executorch/pull/1276

This diff uses the newly added evalue logging API's for two things:
- Logging the args to the delegate call (we can't differentiate between inputs and outputs currently so we log everything, in the future we'd only like to log the outputs)
- Logging the program level outputs after inference is done.

This is essentially a no-op when the `ET_EVENT_TRACER_ENABLED` compilation flag is disabled.

Reviewed By: JacobSzwejbka

Differential Revision: D51534579

fbshipit-source-id: 45ffdb67e5967a95e7262283d6ff37264346c7b4